//計算1、2、3、、、100這100個數的整數和
for語句
#include<stdio.h>
int main()
{
    int a,sum;
    sum = 0;
    for (a = 1; a <= 100; a++)
    {
        sum = sum + a;
    }
    printf("整數和為%d\n",sum);
}
//while迴圈：
{
    int a, sum;
    sum = 0;
    a = 1;
    while (a <= 100){
        sum +=a;
        a++;
    }
    printf("整數和為%d\n"
 
, sum);
}
//do...while語句
{
    int a = 1, sum = 0;
    {
        do{
            sum += a;
            a++;
        }
            while (a <= 100);
        printf("整數和為%d\n", sum);
    }
}