用C语言如何表示1－3＋5－7＋．．．－99＋101

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

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