C语言程序题帮忙解答

如题：

编写程序，求1 -3 +5 -7 +...-99 +101的和的值

#include <stdio.h>

int main()
{
int i, k = 1;
int sum = 0;
for ( i = 1; i <= 101; i += 2 ) {
sum += i*k;
k = -k;
}
printf( "1-3+5-7+...-99+101=%d\n", sum );
return 0;
}

#include<stdio.h>

void main()

{

int sum=0,n=1;

for(int i=1;i<=101;i=i+2)

{

sum=sum+n*i;

n=-n;

}

printf("%d\n",sum); }