為什么這個(gè)算出的結(jié)果是sum=0?想不明白

#include <stdio.h>
int main()
{
??? int sum = 0;? //定義計(jì)算結(jié)果變量sum
??? int i = 1;??? //定義循環(huán)數(shù)字變量i
??? int flag = 1; //定義符號(hào)狀態(tài)變量flag
???
??
??? for(i=1;i<=100;i++)
??? {
??????? if(i%2==0)
??????? {
??????????? flag=(-1)*flag;
??????? }
??????? sum=sum+i*flag;
??? }?
??? printf("sum=%d\n",sum);
???
??? return 0;???
}

淺淺時(shí)光8

2016-04-01

源自：C語言入門 4-10

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2 回答

mango2
2016-04-02

反了~ 而且? if(i%2==0) 應(yīng)該是? if(i%2>=0)

#include <stdio.h>
int main()
{
??? int sum = 0;? //定義計(jì)算結(jié)果變量sum
??? int i = 1;??? //定義循環(huán)數(shù)字變量i
??? int flag = 1; //定義符號(hào)狀態(tài)變量flag
? ?
?
??? for(i=1;i<=100;i++)
??? {
??????? if(i%2>=0)
??????? {
??????? sum+=i*flag;
??????? }
??????? flag*=-1;
??? }
??? printf("sum=%d\n",sum);
? ?
??? return 0;? ?
}