4. (C) Write a program to find the sum of numbers from 1 to 100

4. (C) Write a program to find the sum of numbers from 1 to 100

Sum of Natural Numbers Using while Loop

#include <stdio.h>
	int main()
	{
	int n, i, sum = 0;
	printf("Enter a positive integer: ");
	scanf("%d",&n);
	i = 1;
	while ( i <=n )
	{
	sum += i;
	++i;
	}
	printf("Sum = %d",sum);
	return 0;
	}

Sum of Natural Numbers Using for Loop

#include <stdio.h>
	int main()
	{
	int n, i, sum = 0;
	printf("Enter a positive integer: ");
	scanf("%d",&n);
	for(i=1; i <= n; ++i)
	{
	sum += i; // sum = sum+i;
	}
	printf("Sum = %d",sum);
	return 0;
	}

Program to Read Input Until User Enters a Positive Integer

#include <stdio.h>
	int main()
	{
	int n, i, sum = 0;
	do {
	printf("Enter a positive integer: ");
	scanf("%d",&n);
	}
	while (n <= 0);
	for(i=1; i <= n; ++i)
	{
	sum += i; // sum = sum+i;
	}
	printf("Sum = %d",sum);
	return 0;
	}