Python Program to Subtract Two Binary Numbers

We are given two binary numbers, num1 and num2 and we have to subtract these two binary numbers and return the result. In this article, we will see how we can subtract two binary numbers in Python.

Examples:

Input: a = "1110" , b = "0110"
Output: "1000"
Explanation: We can see that when "1110" is subtracted from "0110" then the answer is "1000" i.e, 14 - 6 = 8.

Python Program to Subtract Two Numbers Binary

Below, are the methods of Python programs to subtract two numbers binary in Python:

• Naive Approach
• Using int() function
• Using sub() function
• Using 2’s Complement

Subtract Two Numbers Binary Using Naive Approach

In this example, below code defines two functions, binary_to_decimal and decimal_to_binary, to convert binary numbers to decimal and vice versa. The program then subtracts two binary numbers, “1110” and “1010,” by converting them to decimal, performing the subtraction, and converting the result back to binary

Python3

# code
def binary_to_decimal(binary):
    decimal = 0
    power = len(binary) - 1
    for digit in binary:
        decimal += int(digit) * (2 ** power)
        power -= 1
    return decimal

def decimal_to_binary(decimal):
    binary = ""
    while decimal > 0:
        remainder = decimal % 2
        binary = str(remainder) + binary
        decimal = decimal // 2
    return binary


num1 = "1110"
num2 = "0110"

print("num1:", num1, "and num2:", num2)

a = binary_to_decimal(num1)
b = binary_to_decimal(num2)

# The resultant difference of decimal numbers
temp = a - b

# converting the subtraction output back to binary
ans = decimal_to_binary(temp)

print("The subtraction result is:", ans)

Output

num1: 1110 and num2: 0110
The subtraction result is: 1000

Subtract Two Numbers Binary Using int() Function

In this example, below code subtracts two binary numbers, “1110” and “1010,” by converting them to decimal using `int()` and then back to binary with `bin()`. It succinctly demonstrates Python’s simplicity in performing binary arithmetic operations.

Python3

num1 = "1110"
num2 = "0110"
print("num1:", num1, "and num2:", num2)

ans = int(num1, 2) - int(num2, 2)
print("The subtraction using int() function:", bin(ans)[2:])

Output

num1: 1110 and num2: 0110
The subtraction using int() function: 1000

Subtract Two Numbers Binary Using sub() Function

In this example, below code utilizes the sub() function from the operator module to subtract two binary numbers, “1110” and “1010,” after converting them to decimal. It then converts the subtraction result back to binary and displays it.

Python3

from operator import *

num1 = "1110"
num2 = "0110"
print("num1:", num1, "and num2:", num2)

ans = sub(int(num1, 2), int(num2, 2))
print("The subtraction using sub() function:", bin(ans)[2:])

Output

num1: 1110 and num2: 0110
The subtraction using sub() function: 1000

Subtract Two Numbers Binary Using 2’s Complement

In this example, below code defines a subtraction function, subtraction, which utilizes the two’s complement representation to subtract two binary numbers. It then subtracts “1110” and “1010” by converting them to decimal, performs the subtraction, and displays the result in binary form

Python3

def subtraction(num1, num2):
    return num1 + (~num2 + 1)

num1 = "1110"
num2 = "0110"
print("num1:", num1, "and num2:", num2)
ans = subtraction(int(num1, 2), int(num2, 2))
print("The subtraction using 2's Complement:", bin(ans))

Output

num1: 1110 and num2: 0110
The subtraction using 2's Complement: 0b1000

Conclusion

In conclusion, this Python program demonstrates a straightforward yet insightful approach to performing binary subtraction. By leveraging the principles of borrow and carry-over in a binary context, the program provides a clear example of how Python can be employed to handle binary arithmetic operations efficiently. This not only highlights the language’s versatility but also underscores its suitability for tasks involving low-level bitwise manipulation.