Python Program to Convert Binary to Decimal using Recursion

In the previous article, we have discussed Python Program for Sign Change
Recursion:

Recursion is the process by which a function calls itself directly or indirectly, and the associated function is known as a recursive function. Certain issues can be addressed fairly easily using a recursive approach. Towers of Hanoi (TOH), Inorder /Preorder/Postorder Tree Traversals, DFS of Graph, and other analogous issues are examples.

Binary Code:

As previously stated, Binary Code is a Base-2 representation of a number. In Binary, all numbers are represented by simply two symbols: 0 and 1. Binary (also known as base-2) is a numerical system with only two digits: 0 and 1.

Given a binary string, the task is to convert the given binary string to a decimal number using recursion in Python.

Examples:

Example1:

Input:

Given binary number = 1011

Output:

The decimal Equivalent of the given binary number { 1011 } is : 11

Example2:

Input:

Given binary number = 10010101

Output:

The decimal Equivalent of the given binary number { 10010101 } is : 149

Program to Convert Binary to Decimal using Recursion in Python

Below are the ways to convert the given binary string to a decimal number using recursion in Python:

Using Recursion (Static Input)
Using Recursion (User Input)

Method #1: Using Recursion (Static Input)

Approach:

Give the binary number as static input and store it in a variable.
Create a recursive function to say binaryToDeci() which accepts the binary number as an argument and returns the decimal equivalent of the given binary string.
Inside the binaryToDeci() function, Check if the binary number is equal to 0 using the if conditional statement.
If it is true then return 0.
Else return (n% 10 + 2* binaryToDeci(n // 10)) {Recursive logic where n%10 gives rightmostbit and n//10 divides the number by 10 which removes the last bit}.
Inside the main function pass the given binary number as an argument to binaryToDeci() which returns the decimal equivalent of the given binary number.
Print the decimal equivalent of the given binary number.
The Exit of the Program.

Below is the implementation:

# Create a recursive function to say binaryToDeci()
# which accepts the binary number as an argument
# and returns the decimal equivalent of the given binary string.


def binaryToDeci(binanumb):
    # Inside the binaryToDeci() function,
    # Check if the binary number is equal to 0 using the if conditional statement.
    if(binanumb == 0):
        # If it is true then return 0.
        return 0
    # Else return (n% 10 + 2* binaryToDeci(n // 10))
    # {Recursive logic where n%10 gives rightmostbit and n//10 divides the number by 10}.
    return (binanumb % 10 + 2 * binaryToDeci(binanumb // 10))


# Give the binary number as static input and store it in a variable.
gvnbinarynumb = 1011
# Inside the main function pass the given binary number as an argument
# to binaryToDeci() which returns the decimal equivalent of the given binary number.
resdecimalnumbr = binaryToDeci(gvnbinarynumb)
# Print the decimal equivalent of the given binary number.
print(
    'The decimal Equivalent of the given binary number {', gvnbinarynumb, '} is :', resdecimalnumbr)

Output:

The decimal Equivalent of the given binary number { 1011 } is : 11

Method #2: Using Recursion (User Input)

Approach:

Give the binary number as user input using int(input()) function and store it in a variable.
Create a recursive function to say binaryToDeci() which accepts the binary number as an argument and returns the decimal equivalent of the given binary string.
Inside the binaryToDeci() function, Check if the binary number is equal to 0 using the if conditional statement.
If it is true then return 0.
Else return (n% 10 + 2* binaryToDeci(n // 10)) {Recursive logic where n%10 gives rightmostbit and n//10 divides the number by 10 which removes the last bit}.
Inside the main function pass the given binary number as an argument to binaryToDeci() which returns the decimal equivalent of the given binary number.
Print the decimal equivalent of the given binary number.
The Exit of the Program.

Below is the implementation:

# Create a recursive function to say binaryToDeci()
# which accepts the binary number as an argument
# and returns the decimal equivalent of the given binary string.


def binaryToDeci(binanumb):
    # Inside the binaryToDeci() function,
    # Check if the binary number is equal to 0 using the if conditional statement.
    if(binanumb == 0):
        # If it is true then return 0.
        return 0
    # Else return (n% 10 + 2* binaryToDeci(n // 10))
    # {Recursive logic where n%10 gives rightmostbit and n//10 divides the number by 10}.
    return (binanumb % 10 + 2 * binaryToDeci(binanumb // 10))


# Give the binary number as user input using int(input()) function
# and store it in a variable.
gvnbinarynumb = int(input('Enter some random binary number = '))
# Inside the main function pass the given binary number as an argument
# to binaryToDeci() which returns the decimal equivalent of the given binary number.
resdecimalnumbr = binaryToDeci(gvnbinarynumb)
# Print the decimal equivalent of the given binary number.
print(
    'The decimal Equivalent of the given binary number {', gvnbinarynumb, '} is :', resdecimalnumbr)

Output:

Enter some random binary number = 10010101
The decimal Equivalent of the given binary number { 10010101 } is : 149

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