Question

C语言编写程序都是计算1-3+5-7+……-99+101的值

Answer 1

#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);

}

Answer 2

可以随便加，由n值决定，你可以输入101
#include <stdio.h>
int main()
{
int n,sum;
printf("Input n:\n");
scanf("%d",&n);
sum=((n+1)/4)*(-2);
if((n+1)%4)
sum+=n;
printf("sum=%d",sum);
}

Answer 3

#include"stdio.h"
main()
{
int i,sum=0,flag=1;
for(i=1;i<=101;i=i+2)
{
sum=sum+i*flag;
flag=-flag;
}
printf("sum=%d\n",sum);
}

Answer 4

#include <stdio.h>

void main()
{
int sum = 0;
int flag = 1;
int i = 0;
for (i = 0; i < 50; i++)
{
sum += flag * (2 * i + 1);
flag = -flag;
}
printf("the result is %d", sum);
}