如何在C ++中显示固定数量的数字而不四舍五入 [英] How to display a fixed number of digits in C++ without rounding

问题描述

我有此代码(非常基本):

I have this code (very basic):

#include <iostream>
#include <iomanip>

using namespace std;
int main()
{
float   a = 0.0,
        b = 0.0,
        c = 0.0;

cout<<"Input a: ";
cin>>a;
cout<<"input b: ";
cin>>b;
cout<<endl;
c = a / b;

cout<<"Result: "<<fixed<<setprecision(2)<<c<<endl;
return 0;
}

当我输入两个数字(例如，a = 513和b = 791)时，我得到0.65.计算器显示正确的答案是0.648.我知道我的代码会将最后一个十进制数字四舍五入，但这不是我想要的.

When I enter two numbers (say, a = 513 and b = 791) I get 0.65. Calculator shows that the correct answer is 0.648. I understand that my code rounds up the last decimal number but this is not what I want.

我如何才能将其保持在0.64而不是0.65的水平?

How can I get it to where it just stays as 0.64 and not 0.65?

推荐答案

如果要将值截断为两位小数，可以将其乘以100，截断为整数，然后除以100，如下所示:

If you would like to truncate the value to two decimal places, you can multiply it by 100, truncate to integer, and then divide by 100, like this:

c = a / b;
c = floor(100 * c) / 100;
cout<<"Result: "<<fixed<<setprecision(2)<<c<<endl;

关于ideone的演示.

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