第二章例2-7

/* 计算1+2+3+…+n */

#include<stdio.h>

int main(void)

{

    int i,n,sum;

    printf("Enter n:");

    scanf_s("%d",&n);

    sum=0;

    for(i=1;i<=n;i++){

        sum=sum+i;

    }


    printf("Sum of numbers from 1 to %d is %d
",n,sum);

    return 0;

}