Question

1,编写程序计算1-3+5-7+......-99+101的值,并输出结果.

Answer 1

试试这个，应该没错：

#include<stdio.h>
#include<stdlib.h>
int main()
{
int i,j;
int plus_flag = 0;
int sum = 0;
for(i=1;i<102;i+=2)
{
if(plus_flag == 0)
{
sum = sum + i;
plus_flag = 1;
}
else
{
sum = sum - i;
plus_flag = 0;
}
}
printf("sum = %d\n",sum);
return 1;
}

Answer 2

#include <stdio.h>
void main()
{
    int a = 0,b = 0,i;
    for(i = 1;i <= 101;i += 4)
        a += i;
    for(i = 3;i <= 99;i += 4)
        b -= i;
    printf("%d\n",a+b);
}