Today we will learn C Program to Add Two Numbers in C and also learn Program to Add Two Numbers in C.

The Addition is the Arithmetic Operation in which the sum of two numbers is performed.

For Example, The addition of 5 and 6 is 11.

## Algorithm of Adding two Numbers

1 Step: START.

2 Step: Initialize integers A, B and C.

3 Step: Accept two integers A and B from User.

3 Step: Now do the operation using formula C=A+B.

4 Step: Now the addition is stored in C Variable.

5 Step: Print C.

6 Step: STOP.

Now we will do this arithmetic operation in C.There are different methods to make Addition in C we will see it one by one.

## 1. Addition Program in C

In this program, we will ask the user to enter the two numbers and do addition using formula. This addition will store in the third Variable and at the end, the value stored in the third variable is printed.

```//c program to add two numbers using third variable C
#include <stdio.h>
int main()
{
int A,B,C;
printf("Enter two integers for addition: ");
scanf("%d %d", &A, &B);
// calculating sum
C = A + B;
printf("The addition of %d and %d is=%d",A,B,C);
return 0;
}```

Output:

## 2. Addition of Two Numbers Without Using Third Variable

In the first program after doing the addition of A and B we store that value in third variable C but, in this program, we will not use the third variable we will store value in same variable A.

```//c program to add two numbers without using third variable
#include <stdio.h>
int main()
{
int A=5,B=7;
// calculating sum
A = A + B;
printf("The addition of 5 and 7 is=%d",A);
return 0;
}```

Output:

This program is not recommended because we have initialized the variables A and B with 5 and 7 we didn’t take numbers from the user and the original value of A is lost.

## 3. C program to Add Two Numbers Repeatedly

The process of addition is same as program one only change is that first program end’s after doing one operation but in this program, we will use while loop which continues the addition until user press n for the exit.

```#include <stdio.h>
int main()
{
int A, B, C;
char ch;
while (1)
{
printf("Input two integers\n");
scanf("%d%d", &A, &B);
getchar();
C = A + B;
printf("(%d) + (%d) = (%d)\n", A, B, C);
printf("Do you wish to add more numbers (y/n)\n");
scanf("%c", &ch);
if (ch == 'y' || ch == 'Y')
continue;
else
break;
}
return 0;
}```

Output:

## 4. Program to Add Two Numbers Using Function

Till now we do not use user-defined functions to calculate the sum of two numbers But, in this program, we will use a user-defined function to do the addition of two numbers.

```//addition using function
#include<stdio.h>
int main()
{
long first, second, sum;
printf("Enter two numbers for addition \n");
scanf("\n%ld\n%ld", &first, &second);
return 0;
}