//#include "stdafx.h"//If the vc++6.0, with this line. #include <iostream> using namespace std; int main(int argc,char *argv[]){ for(int sum,t=0,i=3;i<100;i+=3,t++); sum=i*t/2;//能被3整除的求和 for(t=0,i=7;i<100;i+=7,t++); sum+=i*t/2;//能被7整除的求和 for(t=0,i=21;i<100;i+=21,t++);//把既能被3也能被7整除的减去一个 cout << "The result is " << (sum-=i*t/2) << endl; return 0; }