难以在for循环中定位问题

Question

我正在编写一个程序,用户输入参赛者的名字,并购买比赛门票.我试图弄清楚每个参赛者获胜的几率,但由于某种原因它会返回零,这是代码

for(int i = 0; i < ticPurch.size(); i++){
    totalTics = ticPurch[i] + totalTics;                                              //Figuring out total amount of ticket bought
}
    cout << totalTics;

for (int i = 0; i < names.size(); i++){
    cout << "Contenstant "  << "   Chance of winning " << endl; 
    cout << names[i] << "   " << ((ticPurch.at(i))/(totalTics)) * 100 << " % " << endl; //Figuring out the total chance of winning 

}
    ticPurch is a vector of the the tickets each contestant bought and names is a vector for the contestants name. For some reason the percent is always returning zero and I don't know why

 return 0;

Answer 1

将整数除以整数可以通过截断小数部分来得到整数.

由于您的值小于1,因此结果将始终为零.

您可以将操作数强制转换为浮点类型以获得所需的计算:

(ticPurch.at(i) / (double)totalTics) * 100

然后可能围绕这个结果,因为你似乎想要整数结果:

std::floor((ticPurch.at(i) / (double)totalTics) * 100)

我的首选方法,从而避免了浮点完全(!总是好的),是繁衍到您的计算解决第一:

(ticPurch.at(i) * 100) / totalTics

这将始终向下舍入,因此请注意,如果您决定使用std::round(或std::ceil),而不是std::floor在上面的示例中.如果需要,算术技巧可以模仿那些.

现在,而不是eg (3/5) * 100(即0*100(是0)),你有eg (3*100)/5(即300/5(是60)).