C Program to Add Two Numbers

• Write a C program to add two numbers and print sum on screen.

Before this program, you should read Arithmetic Operators in C

This program takes two numbers as input from user and add them using ‘+’ arithmetic operator and prints the sum on screen. Addition operator in C correspond literally to their respective mathematical operators. If user enters 2 and 3 as input numbers then 5(2 + 3) will be printed as sum on screen.

C program to add two numbers using ‘+’ operator

In this program, we first take two numbers as input from user using scanf function and stores them in integer variable firstNumber and secondNumber. Then we add firstNumber and secondNumber using ‘+’ operator and stores the result in variable ‘sum’. Finally, we print the sum on screen using printf function.

/*
* C Program to print sum of two numbers
*/
#include <stdio.h>
#include <conio.h>
 
int main(){
    /* Integer variable declation */
    int firstNumber, secondNumber, sum;
     
    /* Taking input from user and storing it in firstNumber 
       and secondNumber */
    printf("Enter First Number: ");
    scanf("%d", &firstNumber);
    printf("Enter Second Number: ");
    scanf("%d", &secondNumber);
     
    /* Adding two numbers and storing the result in variable "sum" */
    sum = firstNumber + secondNumber;
    printf("Sum of %d and %d is %d", firstNumber, secondNumber, sum);
    getch();
    return 0;
}
</conio.h></stdio.h>

Program Output

Enter First Number: 2
Enter Second Number: 4
Sum of 2 and 4 is 6

C program to add two numbers using function

This program takes two numbers as input from user and pass it to a user defined function ‘getSum’. Function ‘getSum’ takes two numbers as input parameter and returns sum of the input arguments.

/*
* C Program to Add two numbers using function 
*/
#include <stdio.h>
#include <conio.h>
 
int getSum(int num1, int num2);
int main(){
    /* Integer variable declation */
    int firstNumber, secondNumber, sum;
     
    /* Taking input from user and storing it in firstNumber and secondNumber */
    printf("Enter First Number: ");
    scanf("%d", &firstNumber);
    printf("Enter Second Number: ");
    scanf("%d", &secondNumber);
     
    /* Adding two numbers by calling getSum function 
    and storing the result in variable "sum" */
    sum = getSum(firstNumber, secondNumber);
    printf("Sum of %d and %d is %d", firstNumber, secondNumber, sum);
    getch();
    return 0;
}
/*
* Function to add two numbers
*/
int getSum(int num1, int num2){
    int sum;
    sum = num1 + num2;
    return sum;
}

Program Output

Enter First Number: 4
Enter Second Number: 5
Sum of 2 and 4 is 9

C Program to add two numbers using pointers

This program uses two integer pointer to store the memory address of two operands. It first takes two integers as input from user using scanf function and stores them in firstNumber and secondNumber integer variable. Next step is to assign the addresses of these two input variables to integer pointers. Then value of operator is used to access the data stored in the memory location pointed by these pointer to find the sum.

/*
* C Program to Add two numbers using pointers
*/
#include <stdio.h>
#include <conio.h>
  
int main(){
    
    int firstNumber, secondNumber, sum;
    /* Pointers declaration */
    int *firstNumberPointer, *secondNumberPointer;
    printf("Enter two numbers \n");
    scanf("%d %d", &firstNumber, &secondNumber);
    /* Pointer assignment*/
    firstNumberPointer = &firstNumber;
    secondNumberPointer = &secondNumber;
    
    sum = *firstNumberPointer + *secondNumberPointer;
    printf("SUM = %d", sum);
    getch();
    return 0;
}

Program Output

Enter two numbers 
3 8
SUM = 11