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Addition of two numbers in C

Addition of two numbers in C: This C language program performs the basic arithmetic operation of addition of two numbers and then prints their sum on the screen. For example, if a user will input two numbers as; '5', '6' then '11' (5 + 6) will be printed on the screen. In the expression (c = a + b) overflow may occur if the sum of a and b is larger than the maximum value which can be stored in the variable c. Similarly, you can write a C program which performs subtraction, multiplication, and division of two numbers.

Addition program in C

#include<stdio.h>
 
int main()
{
   int a, b, c;
 
   printf("Enter two numbers to add\n");
   scanf("%d%d", &a, &b);
 
   c = a + b;
 
   printf("Sum of the numbers = %d\n", c);
 
   return 0;
}

Output of C addition program:
Addition C program output.

Download Add numbers program executable.

In the expression (c = a + b) overflow may occur if the sum of a and b is larger than the maximum value which can be stored in the variable c. Similarly, you can write a C program which performs subtraction, multiplication, and division of two numbers.

Addition without using third variable

#include<stdio.h>
 
main()
{
   int a = 1, b = 2;
 
   /* Storing result of addition in variable a */
 
   a = a + b;
 
   printf("Sum of a and b = %d\n", a);
 
   return 0;
}

This method isn't recommended because the original value of the variable 'a' is lost and if we require it further in the program, then we will not have it.

C program to add two numbers repeatedly

#include <stdio.h>
 
int main()
{
   int a, b, c;
   char ch;
 
   while (1) {
      printf("Inut 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 of program:

Inut two integers
2 6
(2) + (6) = (8)
Do you wish to add more numbers (y/n)
y
Inut two integers
2 -6
(2) + (-6) = (-4)
Do you wish to add more numbers (y/n)
y
Inut two integers
-5 3
(-5) + (3) = (-2)
Do you wish to add more numbers (y/n)
y
Inut two integers
-5 -6
(-5) + (-6) = (-11)
Do you wish to add more numbers (y/n)
n

C program for addition of two numbers using a function

We can calculate sum of two integers using a function.

#include<stdio.h>
 
long addition(long, long);
 
main()
{
   long first, second, sum;
 
   scanf("%ld%ld", &first, &second);
 
   sum = addition(first, second);
 
   printf("%ld\n", sum);
 
   return 0;
}
 
long addition(long a, long b)
{
   long result;
 
   result = a + b;
 
   return result;
}

We have used long data type as it can handle large numbers if you want to add very large numbers which don't fit in long range then use an array, a string or other suitable data structure.