Question

用C++编写一个程序求1-3+5-7+9-11....

Answer 1

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