计算sum=1-2+3-4+5-6+7+…+m

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#include <stdio.h>
int sum(void)
{
int i,s,fg=1;
for (s=0,i=1; i <= 10; i++) {
s+=i*fg;
fg*=-1;
}
return s;
}
int main(void)
{
printf("%d",sum());
return 0;
}
//---------------------------------------------------------------------------
再问： 个 是C# 不是C++