Chapter 3: Working with Functions

Checkpoint 3.1

Question 1

If return statement is not used inside the function, the function will return:

0
None object
an arbitrary integer
Error! Functions in Python must have a return statement.

Answer

None object

Reason — The default return value for a function that does not return any value explicitly is None.

Question 2

Which of the following keywords marks the beginning of the function block?

func
define
def
function

Answer

def

Reason — The function in Python is defined as per following syntax :

def function_name(parameters):
    statements

According to this format, function definition begins with keyword def.

Question 3

What is the area of memory called, which stores the parameters and local variables of a function call ?

a heap
storage area
a stack
an array

Answer

a stack

Reason — A stack is the area of memory, which stores the parameters and local variables of a function call.

Question 4

Find the errors in following function definitions :

```
 def main()  
     print ("hello")
```
```
def func2():  
     print(2 + 3)
```
```
def compute():   
     print (x * x)
```
```
square (a)  
     return a * a  
```

Answer

Colon is missing at the end of function header.
There is no error.
The variable x is not defined.
def keyword at the beginning and colon at the end of function header are missing.

The corrected function definitions are:

```
 def main():  
     print("hello")
```
```
 def func2():  
     print(2 + 3)  
```
```
 def compute(x):  
     print (x * x)  
```
```
 def square(a):  
     return a * a 
```

Multiple Choice Questions

Question 1

What is the default return value for a function that does not return any value explicitly ?

None
int
double
null

Answer

None

Reason — The default return value for a function that does not return any value explicitly is None.

Question 2

Which of the following items are present in the function header ?

function name only
both function name and parameter list
parameter list only
return value

Answer

both function name and parameter list

Reason — Function header is the first line of function definition that begins with keyword def and ends with a colon (:), specifies the name of the function and its parameters.

Question 3

Which of the following keywords marks the beginning of the function block ?

func
define
def
function

Answer

def

Reason — The function in Python is defined as per following format :

def function_name(parameters):
    statements

According to this format, function definition begins with keyword def.

Question 4

What is the name given to that area of memory, where the system stores the parameters and local variables of a function call ?

a heap
storage area
a stack
an array

Answer

a stack

Reason — A stack is the area of memory, which stores the parameters and local variables of a function call.

Question 5

Pick one the following statements to correctly complete the function body in the given code snippet.

def f(number):  
    #Missing function body  
print(f(5))

return "number"
print(number)
print("number")
return number

Answer

return number

Reason — The syntax of return statement is :
return <value>
According to this, the correct return statement is return number.

Question 6

Which of the following function headers is correct ?

def f(a = 1, b):
def f(a = 1, b, c = 2):
def f(a = 1, b = 1, c = 2):
def f(a = 1, b = 1, c = 2, d):

Answer

def f(a = 1, b = 1, c = 2):

Reason — In a function header, any parameter cannot have a default value unless all parameters appearing on its right have their default values.

Question 7

Which of the following statements is not true for parameter passing to functions ?

You can pass positional arguments in any order.
You can pass keyword arguments in any order.
You can call a function with positional and keyword arguments.
Positional arguments must be before keyword arguments in a function call.

Answer

You can pass positional arguments in any order.

Reason — Positional arguments are passed to a function based on their positions in the function call statement. The first positional argument in the function call is assigned to the first parameter in the function definition, the second positional argument is assigned to the second parameter, and so on.

Question 8

Which of the following is not correct in context of Positional and Default parameters in Python functions ?

Default parameters must occur to the right of Positional parameters.
Positional parameters must occur to the right of Default parameters.
Positional parameters must occur to the left of Default parameters.
All parameters to the right of a Default parameter must also have Default values.

Answer

Positional parameters must occur to the right of Default parameters.

Reason — The positional parameters must occur to the left of default parameters because in a function header, any parameter cannot have a default value unless all parameters appearing on its right have their default values.

Question 9

Which of the following is not correct in context of scope of variables ?

Global keyword is used to change value of a global variable in a local scope.
Local keyword is used to change value of a local variable in a global scope.
Global variables can be accessed without using the global keyword in a local scope.
Local variables cannot be used outside its scope.

Answer

Local keyword is used to change value of a local variable in a global scope.

Reason — If you need to modify a local variable in global scope, you do so by passing it as an argument to a function and/or returning a modified value from the function.

Question 10

Which of the following function calls can be used to invoke the below function definition ?
def test(a, b, c, d)

test(1, 2, 3, 4)
test(a = 1, 2, 3, 4)
test(a = 1, b = 2, c = 3, 4)
test(a = 1, b = 2, c = 3, d = 4)

Answer

test(1, 2, 3, 4)
test(a = 1, b = 2, c = 3, d = 4)

Reason —

The function call test(1, 2, 3, 4) passes four positional arguments 1, 2, 3, and 4 to the function.
The function call test(a = 1, b = 2, c = 3, d = 4) passes four keyword arguments, explicitly stating the parameter names (a, b, c, d) and their corresponding values.

Question 11

Which of the following function calls will cause Error while invoking the below function definition ?
def test(a, b, c, d)

test(1, 2, 3, 4)
test(a = 1, 2, 3, 4)
test(a = 1, b = 2, c = 3, 4)
test(a = 1, b = 2, c = 3, d = 4)

Answer

test(a = 1, 2, 3, 4)
test(a = 1, b = 2, c = 3, 4)

Reason — In both of these function call test(a = 1, 2, 3, 4) and test(a = 1, b = 2, c = 3, 4), the syntax is incorrect because when using keyword arguments, all arguments following the first one must also be specified with keyword arguments.

Question 12

For a function header as follows :
def Calc(X,Y = 20):
Which of the following function calls will give an error ?

Calc(15, 25)
Calc(X = 15, Y = 25)
Calc(Y = 25)
Calc(X = 25)

Answer

Calc(Y = 25)

Reason — The function call statement must match the number and order of arguments as defined in the function definition. Here, the X positional argument is missing.

Question 13

What is a variable defined outside all the functions referred to as ?

A static variable
A global variable
A local variable
An automatic variable

Answer

A global variable

Reason — A global variable is a variable declared in top level segment (__main__) of a program and usable inside the whole program and all blocks contained within the program.

Question 14

What is a variable defined inside a function referred to as

A static variable
A global variable
A local variable
An automatic variable

Answer

A local variable

Reason — A local variable is a variable declared in a function-body and it can be used only within this function and the other blocks contained under it.

Question 15

Carefully observe the code and give the answer.

def function1(a):
    a = a + '1'
        a = a * 2
>>>function1("hello")

indentation Error
cannot perform mathematical operation on strings
hello2
hello2hello2

Answer

indentation error

Reason — The line a = a * 2 should be indented backwards otherwise it will give an error.

Question 16

What is the result of this code ?

def print_double(x):
    print(2 ** x)
print_double(3)

Answer

Reason — The code defines a function named print_double that takes one parameter x. Inside the function, it calculates 2 raised to the power of x using the exponentiation operator **, and then prints the result. So, when we call print_double(3), we're passing 3 as an argument to the function. The function calculates 2 ** 3, which is 8, and prints the result.

Question 17

What is the order of resolving scope of a name in a Python program ?

B G E L
L E G B
G E B L
L B E G

Answer

L E G B

Reason — When you access a variable from within a program or function, python follows name resolution rule, also known as LEGB rule. When python encounters a name (variable or function), it first searches the local scope (L), then the enclosing scope (E), then the global scope (G), and finally the built-in scope (B).

Question 18

Which of the given argument types can be skipped from a function call ?

positional arguments
keyword arguments
named arguments
default arguments

Answer

default arguments

Reason — A default argument is an argument with a default value in the function header, making it optional in the function call. The function call may or may not have a value for it.

Fill in the Blanks

Question 1

A function is a subprogram that acts on data and often returns a value.

Question 2

Python names the top level segment (main program) as __main__.

Question 3

In Python, program execution begins with first statement of __main__ segment.

Question 4

The values being passed through a function-call statement are called arguments / actual parameters / actual arguments.

Question 5

The values received in the function definition/header are called parameters / formal parameters / formal arguments.

Question 6

A parameter having default value in the function header is known as a default parameter.

Question 7

A default argument can be skipped in the function call statement.

Question 8

Keyword arguments are the named arguments with assigned values being passed in the function call statement.

Question 9

A void function also returns a None value to its caller.

Question 10

By default, Python names the segment with top-level statements (main program) as __main__.

Question 11

The flow of execution refers to the order in which statements are executed during a program run.

Question 12

False

Reason — Variables defined inside functions have only local scope. This means that they are only accessible within the function in which they are defined.

Question 11

A local variable having the same name as that of a global variable, hides the global variable in its function.

Answer

True

Reason — Inside a function, you assign a value to a name which is already there in a global scope, Python won't use the global scope variable because it is an assignment statement and assignment statement creates a variable by default in current environment. That means a local variable having the same name as that of a global variable, hides the global variable in its function.

Assertions and Reasons

Question 1

Assertion. A function is a subprogram.

Reason. A function exists within a program and works within it when called.

Answer

(a)

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation
A function is a subprogram that acts on data and often returns a value. It is a self-contained unit of code that performs a specific task within a larger program. Functions are defined within a program and can be called upon to execute a specific set of instructions when needed.

Question 2

Assertion. Non-default arguments cannot follow default arguments in a function call.

Reason. A function call can have different types of arguments.

Answer

(b)

Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

Explanation
In a function call, any parameter cannot have a default value unless all parameters appearing on its right have their default values. Hence, non-default arguments cannot follow default arguments in a function call. Python supports three types of formal arguments :

Positional arguments
Default arguments
keyword arguments

Type A: Short Answer Questions/Conceptual Questions

Question 1

A program having multiple functions is considered better designed than a program without any functions. Why ?

Answer

A program having multiple functions is considered better designed than a program without any functions because

It makes program handling easier as only a small part of the program is dealt with at a time, thereby avoiding ambiguity.
It reduces program size.
Functions make a program more readable and understandable to a programmer thereby making program management much easier.

Question 2

What all information does a function header give you about the function ?

Answer

Function header is the first line of function definition that begins with keyword def and ends with a colon (:), specifies the name of the function and its parameters.

Question 3

What do you understand by flow of execution ?

Answer

Flow of execution refers to the order in which statements are executed during a program run.

Question 4

What are arguments ? What are parameters ? How are these two terms different yet related ? Give example.

Answer

Arguments — The values being passed through a function-call statement are called arguments.

Parameters — The values received in the function definition/header are called parameters.

Arguments appear in function call statement whereas parameters appear in function header. The two terms are related because the values passed through arguments while calling a function are received by parameters in the function definition.

For example :

def multiply(a, b):
    print(a * b)
multiply(3, 4)

Here, a and b are parameters while 3, 4 are arguments.

Question 5

What is the utility of : (i) default arguments, (ii) keyword arguments ?

Answer

(i) Default arguments — Default arguments are useful in case a matching argument is not passed in the function call statement. They give flexibility to specify the default value for a parameter so that it can be skipped in the function call, if needed. However, still we cannot change the order of the arguments in the function call.

(ii) Keyword arguments — Keyword arguments are useful when you want to specify arguments by their parameter names during a function call. This allows us to pass arguments in any order, as long as we specify the parameter names when calling the function. It also makes the function call more readable and self-explanatory.

Question 6

Explain with a code example the usage of default arguments and keyword arguments.

Answer

Default arguments — Default arguments are used to provide a default value to a function parameter if no argument is provided during the function call.

For example :

def greet(name, message="Hello"):
    print(message, name)

greet("Alice")          
greet("Bob", "Hi there")

Output

Hello Alice
Hi there Bob

In this example, the message parameter has a default value of "Hello". If no message argument is provided during the function call, the default value is used.

Keyword arguments — Keyword arguments allow us to specify arguments by their parameter names during a function call, irrespective of their position.

def person(name, age, city):
    print(name, "is", age, "years old and lives in", city)

person(age=25, name="Alice", city="New York")
person(city="London", name="Bob", age=30)

Output

Alice is 25 years old and lives in New York
Bob is 30 years old and lives in London

In this example, the arguments are provided in a different order compared to the function definition. Keyword arguments specify which parameter each argument corresponds to, making the code more readable and self-explanatory.

Both default arguments and keyword arguments provide flexibility and improve the readability of code, especially in functions with multiple parameters or when calling functions with optional arguments.

Question 7

Describe the different styles of functions in Python using appropriate examples.

Answer

The different styles of functions in Python are as follows :

Built-in functions — These are pre-defined functions and are always available for use. For example:
```
name = input("Enter your name: ")
name_length = len(name)
print("Length of your name:", name_length)
```
In the above example, print(), len(), input() etc. are built-in functions.

User defined functions — These are defined by programmer. For example:

def calculate_area(length, width):
     area = length * width
     return area
length = 5
width = 3
result = calculate_area(length, width)
print("Area of the rectangle:", result)

In the above example, calculate_area is a user defined function.

Functions defined in modules — These functions are pre-defined in particular modules and can only be used when corresponding module is imported. For example:
```
import math
num = 16
square_root = math.sqrt(num)
print("Square root of", num, ":", square_root)
```
In the above example, sqrt is a function defined in math module.

Question 8

Differentiate between fruitful functions and non-fruitful functions.

Answer

Fruitful functions	Non-fruitful functions
Functions returning some value are called as fruitful functions.	Functions that does not return any value are called as non-fruitful functions.
They are also called as non-void functions.	They are also called as void functions.
They have return statements in the syntax : `return<value>`.	They may or may not have a return statement, but if they do, it typically appears as per syntax : `return`.
Fruitful functions return some computed result in terms of a value.	Non-fruitful functions return legal empty value of Python, which is `None`, to their caller.

Question 9

Can a function return multiple values ? How ?

Answer

Yes, a function can return multiple values. To return multiple values from a function, we have to ensure following things :

1. The return statement inside a function body should be of the form :

return <value1/variable1/expression1>,<value2/variable2/expression2>,....

2. The function call statement should receive or use the returned values in one of the following ways :

(a) Either receive the returned values in form a tuple variable.

(b) Or we can directly unpack the received values of tuple by specifying the same number of variables on the left-hand side of the assignment in function call.

Question 10

What is scope ? What is the scope resolving rule of Python ?

Answer

Scope refers to part(s) of program within which a name is legal and accessible. When we access a variable from within a program or function, Python follows name resolution rule, also known as LEGB rule. When Python encounters a name (variable or function), it first searches the local scope (L), then the enclosing scope (E), then the global scope (G), and finally the built-in scope (B).

Question 11

What is the difference between local and global variable ?

Answer

Local variable	Global variable
A local variable is a variable defined within a function.	A global variable is a variable defined in the 'main' program.
They are only accessible within the block in which they are defined.	They are accessible from anywhere within the program, including inside functions.
These variables have local scope.	These variables have global scope.
The lifetime of a local variable is limited to the block of code in which it is defined. Once the execution exits that block, the local variable is destroyed, and its memory is released.	Global variables persist throughout the entire execution of the program. They are created when the program starts and are only destroyed when the program terminates.

Question 12

When is global statement used ? Why is its use not recommended ?

Answer

If we want to assign some value to the global variable without creating any local variable then global statement is used. It is not recommended because once a variable is declared global in a function, we cannot undo the statement. That is, after a global statement, the function will always refer to the global variable and local variable cannot be created of the same name. Also, by using global statement, programmers tend to lose control over variables and their scopes.

Question 13

Write the term suitable for following descriptions :

(a) A name inside the parentheses of a function header that can receive a value.

(b) An argument passed to a specific parameter using the parameter name.

(d) A value assigned to a parameter name in the function header.

(e) A value assigned to a parameter name in the function call.

(f) A name defined outside all function definitions.

(g) A variable created inside a function body.

Answer

(a) Parameter

(b) Keyword argument

(d) Default value

(e) Keyword argument

(f) Global variable

(g) Local variable

Question 14

What do you understand by local and global scope of variables ? How can you access a global variable inside the function, if function has a variable with same name.

Answer

Local scope — Variables defined within a specific block of code, such as a function or a loop, have local scope. They are only accessible within the block in which they are defined.

Global scope — Variables defined outside of any specific block of code, typically at the top level of a program or module, have global scope. They are accessible from anywhere within the program, including inside functions.

To access a global variable inside a function, even if the function has a variable with the same name, we can use the global keyword to declare that we want to use the global variable instead of creating a new local variable. The syntax is :

global<variable name>

For example:

def state1():
    global tigers
    tigers = 15 
    print(tigers)
tigers = 95
print(tigers)
state1()
print(tigers)

In the above example, tigers is a global variable. To use it inside the function state1 we have used global keyword to declare that we want to use the global variable instead of creating a new local variable.

Type B: Application Based Questions

Question 1(a)

What are the errors in following codes ? Correct the code and predict output :

total = 0;
    def sum(arg1, arg2): 
    total = arg1 + arg2;
    print("Total :", total) 
return total;
sum(10, 20);
print("Total :", total)

Answer

total = 0
def sum(arg1, arg2):  
    total = arg1 + arg2
    print("Total :", total) 
    return total
sum(10, 20)
print("Total :", total)

Output

Total : 30
Total : 0

Explanation

There is an indentation error in second line.
The return statement should be indented inside function and it should not end with semicolon.
Function call should not end with semicolon.

Question 1(b)

What are the errors in following codes ? Correct the code and predict output :

def Tot(Number) #Method to find Total
    Sum = 0
    for C in Range (1, Number + 1): 
        Sum += C
        RETURN Sum
print (Tot[3])  #Function Calls
print (Tot[6])

Answer

def Tot(Number): #Method to find Total
    Sum = 0
    for C in range(1, Number + 1): 
        Sum += C
    return Sum
print(Tot(3))  #Function Calls
print(Tot(6))

Output

6
21

Explanation

There should be a colon (:) at the end of the function definition line to indicate the start of the function block.
Python's built-in function for generating sequences is range(), not Range().
Python keywords like return should be in lowercase.
When calling a function in python, the arguments passed to the function should be enclosed inside parentheses () not square brackets [].

Question 2

Find and write the output of the following python code :

def Call(P = 40, Q = 20):
    P = P + Q
    Q = P - Q 
    print(P, '@', Q)
    return P
R = 200
S = 100
R = Call(R, S)
print(R, '@', S) 
S = Call(S)
print(R, '@', S)

Answer

Output

Explanation

Function Call is defined with two parameters P and Q with default values 40 and 20 respectively.
Inside the function Call, P is reassigned to the sum of its original value P and the value of Q.
Q is reassigned to the difference between the new value of P and the original value of Q.
Prints the current values of P and Q separated by @.
The function returns the final value of P.
Two variables R and S are initialized with values 200 and 100 respectively.
The function Call is called with arguments R and S, which are 200 and 100 respectively. Inside the function, P becomes 200 + 100 = 300 and Q becomes 300 - 100 = 200. So, 300 and 200 are printed. The function returns 300, which is then assigned to R. Therefore, R becomes 300.
S = Call(S) — The function Call is called with only one argument S, which is 100. Since the default value of Q is 20, P becomes 100 + 20 = 120, and Q becomes 120 - 20 = 100. So, 120 and 100 are printed. The function returns 120, which is then assigned to S. Therefore, S becomes 120.

Question 3

Consider the following code and write the flow of execution for this. Line numbers have been given for your reference.

1. def power(b, p):
2.  y = b ** p
3.  return y
4. 
5. def calcSquare(x):
6.  a = power(x, 2)
7.  return a
8.
9.  n = 5
10. result = calcSquare(n)
11. print(result)

Answer

The flow of execution for the above program is as follows :

1 → 5 → 9 → 10 → 5 → 6 → 1 → 2 → 3 → 6 → 7 → 10 → 11

Explanation

Line 1 is executed and determined that it is a function header, so entire function-body (i.e., lines 2 and 3) is ignored. Line 5 is executed and determined that it is a function header, so entire function-body (i.e., lines 6 and 7) is ignored. Lines 9 and 10 are executed, line 10 has a function call, so control jumps to function header (line 5) and then to first line of function-body, i.e., line 6, it has a function call , so control jumps to function header (line 1) and then to first line of function-body, i.e, line 2. Function returns after line 3 to line 6 and then returns after line 7 to line containing function call statement i.e, line 10 and then to line 11.

Question 4

What will the following function return ?

def addEm(x, y, z):
    print(x + y + z)

Answer

The function addEm will return None. The provided function addEm takes three parameters x, y, and z, calculates their sum, and then prints the result. However, it doesn't explicitly return any value. In python, when a function doesn't have a return statement, it implicitly returns None. Therefore, the function addEm will return None.

Question 5

What will the following function print when called ?

def addEm(x, y, z):
    return x + y + z
    print(x + y + z)

Answer

The function addEm prints nothing when called.

Explanation

The function addEm(x, y, z) takes three parameters x, y, and z.
It returns the sum of x, y, and z.
Since the return statement is encountered first, the function exits immediately after returning the sum. The print statement after the return statement is never executed. Therefore, it prints nothing.

Question 6(i)

What will be the output of following program ?

num = 1
def myfunc():
    return num
print(num)
print(myfunc())
print(num)

Answer

Output

1
1
1

Explanation

The code initializes a global variable num with 1. myfunc just returns this global variable. Hence, all the three print statements print 1.

Question 6(ii)

What will be the output of following program ?

num = 1
def myfunc():
    num = 10
    return num
print(num)
print(myfunc())
print(num)

Answer

Output

1
10
1

Explanation

num = 1 — This line assigns the value 1 to the global variable num.
def myfunc() — This line defines a function named myfunc.
print(num) — This line prints the value of the global variable num, which is 1.
print(myfunc()) — This line calls the myfunc function. Inside myfunc function, num = 10 defines a local variable num and assigns it the value of 10 which is then returned by the function. It is important to note that the value of global variable num is still 1 as num of myfunc is local to it and different from global variable num.
print(num) — This line prints the value of the global variable num, which is still 1.

Question 6(iii)

What will be the output of following program ?

num = 1
def myfunc():
    global num
    num = 10
    return num
print(num)
print(myfunc())
print(num)

Answer

Output

1
10
10

Explanation

num = 1 — This line assigns the value 1 to the global variable num.
def myfunc() — This line defines a function named myfunc.
print(num) — This line prints the value of the global variable num, which is 1.
print(myfunc()) — This line calls the myfunc function. Inside the myfunc function, the value 10 is assigned to the global variable num. Because of the global keyword used earlier, this assignment modifies the value of the global variable num to 10. The function then returns 10.
print(num) — This line prints the value of the global variable num again, which is still 1.

Question 6(iv)

What will be the output of following program ?

def display():
    print("Hello", end='')
display()
print("there!")

Answer

Output

Hellothere!

Explanation

The function display prints "Hello" without a newline due to the end='' parameter. When called, it prints "Hello". Outside the function, "there!" is printed on the same line due to the absence of a newline.

Question 7

Predict the output of the following code :

a = 10
y = 5
def myfunc(): 
    y = a
    a = 2
    print("y =", y, "a =", a) 
    print("a + y =", a + y) 
    return a + y
print("y =", y, "a =", a)
print(myfunc())  
print("y =", y, "a =", a)

Answer

The code raises an error when executed.

Explanation

In the provided code, the global variables a and y are initialized to 10 and 5, respectively. Inside the myfunc function, the line a = 2 suggests that a is a local variable of myfunc. But the line before it, y = a is trying to assign the value of local variable a to local variable y even before local variable a is defined. Therefore, this code raises an UnboundLocalError.

Question 8

What is wrong with the following function definition ?

def addEm(x, y, z):  
    return x + y + z
    print("the answer is", x + y + z)

Answer

In the above function definition, the line print("the answer is", x + y + z) is placed after the return statement. In python, once a return statement is encountered, the function exits immediately, and any subsequent code in the function is not executed. Therefore, the print statement will never be executed.

Question 9

Write a function namely fun that takes no parameters and always returns None.

Answer

def fun():
    return

Explanation

def fun():
    return 
r = fun()
print(r)

The function fun() returns None. When called, its return value is assigned to r, which holds None. Then print(r) outputs None.

Question 10

Consider the code below and answer the questions that follow :

def multiply(number1, number2):
    answer = number1 * number2
    print(number1, 'times', number2, '=', answer)
    return(answer)
output = multiply(5, 5)

(i) When the code above is executed, what prints out ?

(ii) What is variable output equal to after the code is executed ?

Answer

(i) When the code above is executed, it prints:

5 times 5 = 25

(ii) After the code is executed, the variable output is equal to 25. This is because the function multiply returns the result of multiplying 5 and 5, which is then assigned to the variable output.

Question 11

Consider the code below and answer the questions that follow :

def multiply(number1, number2):
    answer = number1 * number2
    return(answer)
    print(number1, 'times', number2, '=', answer)
output = multiply(5, 5)

(i) When the code above is executed, what gets printed ?

(ii) What is variable output equal to after the code is executed ?

Answer

(i) When the code above is executed, it will not print anything because the print statement after the return statement won't execute. Therefore, the function exits immediately after encountering the return statement.

Question 12(a)

Find the errors in code given below :

def minus(total, decrement)  
    output = total - decrement                              
    print(output)
    return (output)

Answer

The errors in the code are:

def minus(total, decrement) # Error 1  
    output = total - decrement                              
    print(output)
    return (output)

There should be a colon at the end of the function definition line.

The corrected code is given below:

def minus(total, decrement): 
    output = total - decrement
    print(output)
    return (output)

Question 12(b)

Find the errors in code given below :

define check()
    N = input ('Enter N: ') 
    i = 3                                             
    answer = 1 + i ** 4 / N                              
    Return answer

Answer

The errors in the code are:

define check() #Error 1
    N = input ('Enter N: ') #Error 2
    i = 3                                             
    answer = 1 + i ** 4 / N                              
    Return answer #Error 3

The function definition lacks a colon at the end.
The 'input' function returns a string. To perform arithmetic operations with N, it needs to be converted to a numeric type, such as an integer or a float.
The return statement should be in lowercase.

The corrected code is given below:

def check():
    N = int(input('Enter N:'))
    i = 3
    answer = 1 + i ** 4 / N
    return answer

Question 12(c)

Find the errors in code given below :

def alpha (n, string = 'xyz', k = 10) :
    return beta(string)
    return n

def beta (string)
    return string == str(n)

print(alpha("Valentine's Day"):)
print(beta(string = 'true'))
print(alpha(n = 5, "Good-bye"):)

Answer

The errors in the code are:

def alpha (n, string = 'xyz', k = 10) :
    return beta(string)
    return n #Error 1

def beta (string) #Error 2
    return string == str(n)

print(alpha("Valentine's Day"):) #Error 3
print(beta(string = 'true')) #Error 4
print(alpha(n = 5, "Good-bye"):) #Error 5

The second return statement in the alpha function (return n) is unreachable because the first return statement return beta(string) exits the function.
The function definition lacks colon at the end. The variable n in the beta function is not defined. It's an argument to alpha, but it's not passed to beta explicitly. To access n within beta, we need to either pass it as an argument or define it as a global variable.
There should not be colon at the end in the function call.
In the function call beta(string = 'true'), there should be argument for parameter n.
In the function call alpha(n = 5, "Good-bye"), the argument "Good-bye" lacks a keyword. It should be string = "Good-bye".

The corrected code is given below:

def alpha(n, string='xyz', k=10):
    return beta(string, n)

def beta(string, n):
    return string == str(n)

print(alpha("Valentine's Day"))
print(beta(string='true', n=10))
print(alpha(n=5, string="Good-bye"))

Question 13

Draw the entire environment, including all user-defined variables at the time line 10 is being executed.

1. def sum(a, b, c, d):
2.      result = 0
3.      result = result + a + b + c + d 
4.      return result
5. 
6. def length():
7.      return 4
8. 
9. def mean(a, b, c, d):
10.     return float(sum(a, b, c, d))/length()
11. 
12. print(sum(a, b, c, d), length(), mean(a, b, c, d))

Answer

The environment when the line 10 is being executed is shown below :

Draw the entire environment, including all user-defined variables at the time line 10 is being executed. Python Computer Science Sumita Arora Solutions CBSE Class 12

Question 14

Draw flow of execution for the above program.

Answer

The flow of execution for the above program is as follows :

1 → 6 → 9 → 12 → 1 → 2 → 3 → 4 → 6 → 7 → 9 → 10 → 12

Line 1 is executed and determined that it is a function header, so entire function-body (i.e, lines 2, 3, 4) is ignored.Then line 6 is executed and determined that it is a function header, so entire function-body (i.e, line 7) is ignored, Line 9 is executed and determined that it is a function header, so entire function-body (i.e, line 10) is ignored. Then line 12 is executed and it has a function calls, so control jumps to the function header (line 1) and then first line of function-body, i.e, line 2, function returns after line 4 to function call line (line 12) and then control jumps to line 6, it is a function header and then first line of function-body, i.e., line 7, function returns after line 7 to function call line (line 12) and then control jumps to line 9, it is a function header and then first line of function-body, i.e., line 10, function returns after line 10 to function call line 12.

Question 15

Find and write the output of the following python code :

a = 10
def call(): 
    global a
    a = 15
    b = 20
    print(a) 
call()

Answer

Output

15

Explanation

a = 10 — This line assigns the value 10 to the global variable a.
def call() — This line defines a function named call.
a = 15 — Inside the call function, this line assigns the value 15 to the global variable a. As global keyword is used earlier, this assignment modifies the value of the global variable a.
b = 20 — Inside the call function, this line assigns the value 20 to a local variable b.
print(a) — This line prints the value of the global variable a, which is 15. This is because we've modified the global variable a inside the call function.

Question 16

In the following code, which variables are in the same scope ?

def func1():
    a = 1
    b = 2

def func2():
    c = 3
    d = 4
e = 5

Answer

In the code, variables a and b are in the same scope because they are defined within the same function func1(). Similarly, variables c and d are in the same scope because they are defined within the same function func2(). e being a global variable is not in the same scope.

Question 17

Write a program with a function that takes an integer and prints the number that follows after it. Call the function with these arguments :

4, 6, 8, 2 + 1, 4 - 3 * 2, -3 -2

Answer

1. def print_number(number):
2.    next_number = number + 1
3.    print("The number following", number, "is", next_number)
4. print_number(4)
5. print_number(6)
6. print_number(8)
7. print_number(2 + 1)
8. print_number(4 - 3 * 2)
9. print_number(- 3 - 2)

Output

The print_number following 4 is 5
The print_number following 6 is 7
The print_number following 8 is 9
The print_number following 3 is 4
The print_number following -2 is -1
The print_number following -5 is -4

Explanation

def print_number(number) — This line defines a function named print_number that takes one argument number.
next_number = number + 1 — Inside the print_number function, this line calculates the next number after the input number by adding 1 to it and assigns the result to the variable next_number.
print("The number following", number, "is", next_number) — Inside the print_number function, this line prints a message stating the number and its following number.
Then the print_number function is called multiple times with 4, 6, 8, 3 ,((4 - 3 * 2) = -2), ((-3-2) = -5) as arguments.

Question 18

Write a program with non-void version of above function and then write flow of execution for both the programs.

Answer

The non-void version of above code is as shown below :

1. def print_number(number):
2.    next_number = number + 1
3.    return next_number
4. print(print_number(4))
5. print(print_number(6))
6. print(print_number(8))
7. print(print_number(2 + 1))
8. print(print_number(4 - 3 * 2))
9. print(print_number(-3 - 2))

Output

Explanation

def print_number(number) — This line defines a function named print_number that takes one argument number.
next_number = number + 1 — Inside the print_number function, this line calculates the next number after the input number by adding 1 to it and assigns the result to the variable next_number.
return next_number — Inside the print_number function, this line returns next_number.
Then the print_number function is called multiple times with 4, 6, 8, 3 ,((4 - 3 * 2) = -2), ((-3-2) = -5) as arguments.

The flow of execution for the above program with non-void version is as follows :

1 → 4 → 1 → 2 → 3 → 4 → 5 → 1 → 2 → 3 → 5 → 6 → 1 → 2 → 3 → 6 → 7 → 1 → 2 → 3 → 7 → 8 → 1 → 2 → 3 → 8 → 9 → 1 → 2 → 3 → 9

Line 1 is executed and determined that it is a function header, so entire function-body (i.e., line 2 and 3) is ignored. Then line 4 is executed and it has function call, so control jumps to the function header (line 1) and then to first line of function-body, i.e., line 2, function returns after line 3 to line containing function call statement i.e., line 4. The next lines 5, 6, 7, 8, 9 have function calls so they repeat the above steps.

The flow of execution for the void version program is as follows :

1 → 4 → 1 → 2 → 3 → 4 → 5 → 1 → 2 → 3 → 5 → 6 → 1 → 2 → 3 → 6 → 7 → 1 → 2 → 3 → 7 → 8 → 1 → 2 → 3 → 8 → 9 → 1 → 2 → 3 → 9

Question 19(i)

What is the output of following code fragments ?

def increment(n):
    n.append([4])
    return n
L = [1, 2, 3]
M = increment(L)
print(L, M)

Answer

Output

[1, 2, 3, [4]] [1, 2, 3, [4]]

Explanation

In the code, the function increment appends [4] to list n, modifying it in place. When L = [1, 2, 3], calling increment(L) changes L to [1, 2, 3, [4]]. Variable M receives the same modified list [1, 2, 3, [4]], representing L. Thus, printing L and M results in [1, 2, 3, [4]], confirming they reference the same list. Therefore, modifications made to list inside a function affect the original list passed to the function.

Question 19(ii)

What is the output of following code fragments ?

def increment(n):
    n.append([49])
    return n[0], n[1], n[2], n[3]
L = [23, 35, 47]
m1, m2, m3, m4 = increment(L)
print(L)
print(m1, m2, m3, m4)
print(L[3] == m4)

Answer

Output

[23, 35, 47, [49]]
23 35 47 [49]
True

Explanation

The function increment appends [49] to list n and returns its first four elements individually. When L = [23, 35, 47], calling increment(L) modifies L to [23, 35, 47, [49]]. Variables m1, m2, m3, and m4 are assigned the same list [23, 35, 47, [49]], representing the original list L. Thus, printing L and m1, m2, m3, m4 yields [23, 35, 47, [49]]. The expression L[3] == m4 evaluates to True, indicating that the fourth element of L is the same as m4.

Question 20

What will be the output of the following Python code ?

V = 25
def Fun(Ch):
    V = 50
    print(V, end = Ch) 
    V *= 2
    print(V, end = Ch)
print(V, end = "*")
Fun("!")
print(V)

25*50!100!25
50*100!100!100
25*50!100!100
Error

Answer

25*50!100!25

Explanation

V = 25 — initializes global variable V to 25.
print(V, end = "*") — Prints the global variable V (25) followed by an asterisk without a newline.
Fun("!") — Calls the function Fun with the argument "!".
Inside function Fun, V = 50 initializes a local variable V within the function with the value 50. This variable is different from the global variable V that has the value 25.
print(V, end = Ch) — Prints the local variable V (50) followed by the character passed as an argument to the function, which is "!".
V *= 2 — Multiplies the local variable V (50) by 2, making it 100.
print(V, end = Ch) — Prints the updated local variable V (100) followed by the character "!".
The function Fun returns and the line print(V) is executed. It prints the global variable V without any newline character. The global variable V remains unchanged (25).

Type C: Programming Practice/Knowledge based Questions

Question 1

Write a function that takes amount-in-dollars and dollar-to-rupee conversion price; it then returns the amount converted to rupees. Create the function in both void and non-void forms.

Solution

def convert_dollars_to_rupees(amount_in_dollars, conversion_rate):
    amount_in_rupees = amount_in_dollars * conversion_rate
    return amount_in_rupees

def convert_dollars_to_rupees_void(amount_in_dollars, conversion_rate):
    amount_in_rupees = amount_in_dollars * conversion_rate
    print("Amount in rupees:", amount_in_rupees)

amount = float(input("Enter amount in dollars "))
conversion_rate = float(input("Enter conversion rate "))

# Non-void function call
converted_amount = convert_dollars_to_rupees(amount, conversion_rate)
print("Converted amount (non-void function):", converted_amount)

# Void function call
convert_dollars_to_rupees_void(amount, conversion_rate)

Output

Enter amount in dollars 50
Enter conversion rate 74.5
Converted amount (non-void function): 3725.0
Amount in rupees: 3725.0


Enter amount in dollars 100
Enter conversion rate 75
Converted amount (non-void function): 7500.0
Amount in rupees: 7500.0

Question 2

Write a function to calculate volume of a box with appropriate default values for its parameters. Your function should have the following input parameters :

(a) length of box ;

(b) width of box ;

Test it by writing complete program to invoke it.

Solution

def calculate_volume(length = 5, width = 3, height = 2):
    return length * width * height

default_volume = calculate_volume()
print("Volume of the box with default values:", default_volume)

v = calculate_volume(10, 7, 15)
print("Volume of the box with default values:", v)

a = calculate_volume(length = 23, height = 6)
print("Volume of the box with default values:", a)

b = calculate_volume(width = 19)
print("Volume of the box with default values:", b)

Output

Volume of the box with default values: 30
Volume of the box with default values: 1050
Volume of the box with default values: 414
Volume of the box with default values: 190

Question 3

Write a program to have following functions :

(i) a function that takes a number as argument and calculates cube for it. The function does not return a value. If there is no value passed to the function in function call, the function should calculate cube of 2.

(ii) a function that takes two char arguments and returns True if both the arguments are equal otherwise False.

Test both these functions by giving appropriate function call statements.

Solution

# Function to calculate cube of a number
def calculate_cube(number = 2):
    cube = number ** 3
    print("Cube of", number, "is", cube)

# Function to check if two characters are equal
def check_equal_chars(char1, char2):
    return char1 == char2

calculate_cube(3)
calculate_cube()

char1 = 'a'
char2 = 'b'
print("Characters are equal:", check_equal_chars(char1, char1))
print("Characters are equal:", check_equal_chars(char1, char2))

Output

Cube of 3 is 27
Cube of 2 is 8
Characters are equal: True
Characters are equal: False

Question 4

Write a function that receives two numbers and generates a random number from that range. Using this function, the main program should be able to print three numbers randomly.

Solution

import random

def generate_random_number(num1, num2):
    low = min(num1, num2)
    high = max(num1, num2)
    return random.randint(low, high)

num1 = int(input("Enter the first number: "))
num2 = int(input("Enter the second number: "))

for i in range(3):
    random_num = generate_random_number(num1, num2)
    print("Random number between", num1, "and", num2, ":", random_num)

Output

Enter the first number: 2
Enter the second number: 78
Random number between 2 and 78 : 77
Random number between 2 and 78 : 43
Random number between 2 and 78 : 52

Enter the first number: 100
Enter the second number: 599
Random number between 100 and 599 : 187
Random number between 100 and 599 : 404
Random number between 100 and 599 : 451

Question 5

Write a function that receives two string arguments and checks whether they are same-length strings (returns True in this case otherwise False).

Solution

def same_length_strings(str1, str2):
    return len(str1) == len(str2)

s1 = "hello"
s2 = "world"
s3 = "python"

print(same_length_strings(s1, s2)) 
print(same_length_strings(s1, s3))

Output

True
False

Question 6

Write a function namely nthRoot( ) that receives two parameters x and n and returns nth root of x i.e., x^(1/n).
The default value of n is 2.

Solution

def nthRoot(x, n = 2):
    return x ** (1/n)

x = int(input("Enter the value of x:"))
n = int(input("Enter the value of n:"))

result = nthRoot(x, n)
print("The", n, "th root of", x, "is:", result)

default_result = nthRoot(x)
print("The square root of", x, "is:", default_result)

Output

Enter the value of x:36
Enter the value of n:6
The 6 th root of 36 is: 1.8171205928321397
The square root of 36 is: 6.0

Question 7

Write a function that takes a number n and then returns a randomly generated number having exactly n digits (not starting with zero) e.g., if n is 2 then function can randomly return a number 10-99 but 07, 02 etc. are not valid two digit numbers.

Solution

import random
def generate_number(n):
    lower_bound = 10 ** (n - 1)  
    upper_bound = (10 ** n) - 1   
    return random.randint(lower_bound, upper_bound)

n = int(input("Enter the value of n:"))
random_number = generate_number(n)
print("Random number:", random_number)

Output

Enter the value of n:2
Random number: 10

Enter the value of n:2
Random number: 50

Enter the value of n:3
Random number: 899

Enter the value of n:4
Random number: 1204

Question 8

Write a function that takes two numbers and returns the number that has minimum one's digit.

[For example, if numbers passed are 491 and 278, then the function will return 491 because it has got minimum one's digit out of two given numbers (491's 1 is < 278's 8)].

Solution

def min_ones_digit(num1, num2):
    ones_digit_num1 = num1 % 10
    ones_digit_num2 = num2 % 10
    if ones_digit_num1 < ones_digit_num2:
        return num1
    else:
        return num2

num1 = int(input("Enter first number:"))
num2 = int(input("Enter second number:"))
result = min_ones_digit(num1, num2)
print("Number with minimum one's digit:", result)

Output

Enter first number:491
Enter second number:278
Number with minimum one's digit: 491


Enter first number:543
Enter second number:765
Number with minimum one's digit: 543

Question 9

Write a program that generates a series using a function which takes first and last values of the series and then generates four terms that are equidistant e.g., if two numbers passed are 1 and 7 then function returns 1 3 5 7.

Solution

def generate_series(first, last):
    step = (last - first) // 3
    series = [first, first + step, first + 2 * step, last] 
    return series

first_value = int(input("Enter first value:"))
last_value = int(input("Enter last value:"))
result_series = generate_series(first_value, last_value)
print("Generated Series:", result_series)

Output

Enter first value:1
Enter last value:7
Generated Series: [1, 3, 5, 7]


Enter first value:10
Enter last value:25
Generated Series: [10, 15, 20, 25]

Chapter 3

Working with Functions

Class 12 - Computer Science with Python Sumita Arora

Checkpoint 3.1

Question 1

Question 2

Question 3

Question 4

Multiple Choice Questions

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Fill in the Blanks

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

True/False Questions

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Assertions and Reasons

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Type A: Short Answer Questions/Conceptual Questions

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Output

Output

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Type B: Application Based Questions

Question 1(a)