C Program to find the sum of natural numbers upto n

C Program to find the sum of natural numbers upto n using For Loop

In the below program, we will ask the user to enter the value of ‘n’. After entering the value of ‘n’ we will calculate the sum of natural numbers up to n terms with the help of for loop.

#include<stdio.h>
int main()
{
    int num, i;
    unsigned long int sum = 0;
    printf("Please Enter any Integer number = ");
    scanf("%d", &num);
    if(num >0)
    {
        for(i = 1; i <= num; i++)
        {
            sum += i;
        }
        printf("Sum = %ld\n",sum);
    }
    else
    {
        printf("Enter Valid number\n");
    }
    return 0;
}

Output:

Please Enter any Integer number = 5
Sum = 15

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C Program to find the sum of natural numbers upto n using while Loop

In the below program, we will ask the user to enter the value of ‘n’. After entering the value of ‘n’ we will calculate the sum of natural numbers up to n terms with the help of a while loop.

#include<stdio.h>
int main()
{
    int num, i = 0;
    unsigned long int sum = 0;
    printf("Please Enter any Integer number = ");
    scanf("%d",&num);
    if(num >0)
    {
        while(i <= num)
        {
            sum += i;
            i++;
        }
        printf("Sum = %ld\n",sum);
    }
    else
    {
        printf("Enter Valid number\n");
    }
    return 0;
}

Outout:

Please Enter any Integer number = 5
Sum = 15