是您实际上是尝试舍入数字，还是只是更改其显示精度？

Are you actually trying to round the number, or just change its displayed precision?

对于前者（将多余的数字截断）：

For the former (truncating the extra digits):

double scale = 0.01;  // i.e. round to nearest one-hundreth
value = (int)(value / scale) * scale;

或（根据jheriko的回答，四舍五入）

or (rounding up/down as appropriate, per jheriko's answer)

double scale = 0.01;  // i.e. round to nearest one-hundreth
value = floor(value / scale + 0.5) * scale;

对于后者：

cout << setprecision(2) << value;

其中 setprecision（）的参数为小数点后显示的最大位数。

where the parameter to setprecision() is the maximum number of digits to show after the decimal point.