C Program to Add Two Integers

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Given two integers, the task is to add these integer numbers and return their sum.

Examples

Input: a = 5, b = 3
Output: 8
Explanation: The sum of 5 and 3 is 8.

Input: a = -2, b = 7
Output: 5
Explanation: The sum of -2 and 7 is 5.

In C, we have multiple methods to add two numbers, such as the addition operator (+), or by using bitwise addition, which uses AND and XOR operations, or by simply using the increment operator.

Adding Two Numbers using + Operator

Adding two numbers is a simple task in C language that can be accomplished using the '+' operator that takes two operands and returns their sum as the result. This operator allows you to perform arithmetic addition between integers or floating-point numbers.

C Program to Add Two Numbers using + Operators

// C program to add two numbers
#include <stdio.h>

int main() {
    int a, b, sum = 0;
  
  	// Read two numbers from the user
    printf("Enter two integers: ");
    scanf("%d %d", &a, &b);

    // Calculate the addition of a and b
    // using '+' operator
    sum = a + b;

    printf("Sum: %d", sum);

    return 0;
}

Output

Enter two integers: 5 3
Sum: 8

Time Complexity: O(1)
Auxiliary Space: O(1)

Explanation: In the above program, the user is first asked to enter two numbers. The input is taken using the scanf() function and stored in the variables a and b. Then, the variables a and b are then added using the arithmetic operator + (addition operator), and the result is stored in the variable sum.

Addition Using Increment Operator (++)

We can also add two numbers in C++ using the increment operator by repeatedly increasing the first value based on the value of the second number.

C Program to Add Two Numbers using Bitwise Operators

// C Program to add two numbers using increment operator
#include <iostream>
using namespace std;

int addUsingIncrement(int a, int b) {
    

    return a;
}

int main() {
    int a, b;

    // Input two integers
    cout << "Enter two integers: ";
    cin >> a >> b;
  
  	// If b is positive, increment a b times
    for (int i = 0; i < b; i++) {
        a++;
    }
    
    // If b is negative, decrement a |b| times
    for (int i = 0; i > b; i--) {
        a--;
    }

    // Output the sum
    cout << "Sum = " << a << endl;

    return 0;
}

Output

Enter two integers: 5 3
Sum = 8

Addition Using Bitwise Operators

We can also add two numbers using bitwise operations without using the + operator. This involves using the XOR and AND operation along with bit shifting.

Step-by-Step Approach

• Read two integers from the user.
• Use bitwise XOR (^) operator to add the bits of the numbers without carry.
• Use bitwise AND (&) operator to calculate the carry.
• Left shift (<<) the carry by one place to add it.
• Repeat the process until there is no carry.

C Program to Add Two Numbers using Bitwise Operators

// C program to add two numbers using Bitwise operators
#include <stdio.h>

int main() {
    int a, b, sum, carry;

    // Take two integer numbers from user
    printf("Enter two integers: ");
    scanf("%d %d", &a, &b);

    while (b) {

        // Carry is AND of a and b
        carry = a & b;

        // Sum without carry is XOR of a and b
        a = a ^ b;

        // Carry is shifted by one so that it can be
        // added in the next iteration
        b = carry << 1;
    }
  
    printf("Sum = %d\n", a);
    return 0;
}

Output

Enter two integers: 5 3
Sum = 8