p124 题2.16
有位司机记录了自己每次行驶的路程和每次耗费的汽油量。求每次加油平均一加仑汽油行多少英里。输入-1时 ，求出综 合平均数.

#include <iostream>
using std::cout;
using std::cin;
using std::endl;

int main()
{
double miles;
double gallons;
double gallons_sum=0;
double miles_sum=0;

while (gallons !=-1.0){
cout<<"Enter the gallons used (-1 to end): ";
cin>>gallons;

if (gallons =-1.0)
break;

cout<<"Enter the miles driven: ";
cin>>miles;

cout<<"The average for this time was "<<miles/gallons<<endl;

gallons_sum+=gallons;
miles_sum+=miles;
}

cout<<"The total average is "<<miles_sum/gallons_sum<<endl;

return 0;
}
它总是跳出循环，我还没输-1呢。

[此贴子已经被作者于2006-2-22 14:14:45编辑过]