How To Add Two Numbers Without Using + Operator In Python

In this tutorial, we will learn how to add two numbers in Python without using the conventional ‘+’ operator. Performing addition without using the ‘+’ operator can be both challenging and interesting at the same time. We will be using the bitwise operator for this purpose.

Understanding how bits operate at the basic level and implementing bitwise addition is a good way to improve your comprehension of Python programming.

Before proceeding with the tutorial, make sure you have Python installed on your computer. You can download it from the official Python website here: Python.org

Step 1: Understanding Bitwise Operators

Bitwise operators deal with numbers (integer type) at the bit level, that is, in their binary format. Python provides six different bitwise operators, and we will focus on the bitwise AND and XOR operators for this tutorial.

The bitwise AND operator (‘&’) compares each bit of the first operand to the corresponding bit of the second operand. If both bits are 1, the corresponding result bit is set to 1. Otherwise, the corresponding result bit is set to 0.

The bitwise XOR operator (‘^’) also compares each bit of the first operand to the corresponding bit of the second operand. If the bits are different, the corresponding result bit is set to 1. Otherwise, the corresponding result bit is set to 0.

Step 2: Implementing Bitwise Addition Function

Now that you understand bitwise operators, let’s implement the bitwise addition without using the ‘+’ operator. This can be done using a while loop and the bitwise AND and XOR operators.

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def add(a, b):
    while b:
        carry = a & b
        a = a ^ b
        b = carry << 1
 
    return a

The function takes two numbers as input a and b and adds them by utilizing the bitwise AND and XOR operators and a while loop. We calculate the “carry” using the bitwise AND operator and shift the result to the left by one place (simulating a carry operation). Then, we calculate the sum using the bitwise XOR operator and store it in the variable a. We repeatedly run this loop until the carry becomes zero.

Step 3: Testing the Function

Let’s test this function with two sample numbers:

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a = 5
b = 11
result = add(a, b)
print(f"Sum of {a} and {b} without using + operator is: {result}")

This should give the correct sum of the two numbers as the output.

Full Code

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def add(a, b):
    while b:
        carry = a & b
        a = a ^ b
        b = carry << 1
    return a
 
a = 5
b = 11
result = add(a, b)
print(f"Sum of {a} and {b} without using + operator is: {result}")

Output

Sum of 5 and 11 without using + operator is: 16

Conclusion

In this tutorial, we learned how to add two numbers in Python without using the ‘+’ operator by utilizing bitwise operators. This is an interesting and challenging approach to basic arithmetic operations. Understanding bitwise operators and their applications can broaden your knowledge of Python, making you a more advanced programmer.