C program to calculate the sum of natural numbers

C program to find the sum of natural numbers in using loops

In this tutorial, we will discuss a concept of C program to find the sum of natural numbers using loops

In this article, we are going to learn how to find the sum of natural numbers using loops in the C programming language

C code to find the sum of natural numbers using loop

C code to find the sum of numbers using for loop

Program 1

This program takes input from the user and stores in variable num. Then, the for loop is used to calculate the sum of natural numbers up to the given numbers.

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int num,i,sum=0;

    printf("Enter a positive integer: ");
    scanf("%d",&num);

    for(i=1; i<=num; i++){
        sum+=i;    //sum=sum+i

    }
    printf("Sum of numbers are: %d",sum);
    getch();
    return 0;
}

When the above code is executed, it produces the following results

Enter a positive integer: 100
Sum of numbers are: 5050

C code to find the sum of numbers using while loop

Program 2

This program takes input from the user and stores in variable num. Then the while loop is used to calculate the sum of natural numbers upto the given number.

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int num,i,sum=0;

    printf("Enter a positive integer: ");
    scanf("%d",&num);

    i=1;
    while(i<=num){
        sum+=i;    //sum=sum+i
 i++;
    }
    printf("Sum of numbers are: %d",sum);
    getch();
    return 0;
}

When the above code is executed, it produces the following results

Enter a positive integer: 100
Sum of numbers are: 5050

C code to find the sum of numbers using do-while loop

Program 3

This program takes input from the user and stores in variable num. Then the do-while loop is used to calculate the sum upto the given number.

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int num,i,sum=0;//variable declaration
    printf("Enter a positive integer: ");
    scanf("%d",&num);  //get input from user
    i=1;

do{

    sum+=i;  //sum=sum+i
     i++;
}
    while(i<=num);
          

printf("Sum of numbers are: %d",sum);

    getch();
    return 0;
}

When the above code is executed, it produces the following results

Enter a positive integer: 100
Sum of numbers are: 5050

Method:

The following variables i,num and sum=0 are declared.
A positive integer is received from the user.
Then, the loop is used to add a consecutive number from 1 up to the given number.
Finally, the sum is received as output and displayed.