Positive integers 1, 2, 3, 4… are known as natural numbers. This program takes a positive integer from user( suppose user entered n ) then, this program displays the value of 1+2+3+….n.
Example of C Program to Calculate Sum of Natural Numbers
Program 1
/* This program is solved using while loop. */
#include <stdio.h>
int main()
{
int n, count, sum=0;
printf("Enter an integer: ");
scanf("%d",&n);
count=1;
while(count<=n) /* while loop terminates if count>n */
{
sum+=count; /* sum=sum+count */
++count;
}
printf("Sum = %d",sum);
return 0;
}
Program 2
/* This program is solve using for loop. */
#include <stdio.h>
int main()
{
int n, count, sum=0;
printf("Enter an integer: ");
scanf("%d",&n);
for(count=1;count<=n;++count) /* for loop terminates if count>n */
{
sum+=count; /* sum=sum+count */
}
printf("Sum = %d",sum);
return 0;
}
Output
Enter an integer: 100 Sum = 5050
