如何限制“e”之前的小数位？(How do I limit the decimal places before “e”?)

如何限制“e”之前的小数位？(How do I limit the decimal places before “e”?)

我想在格式为“1.00e6”的C ++中打印一个浮点变量x，其中我只想在e之前的小数点后2位。

阅读本文： http ： //www.cplusplus.com/reference/cstdio/printf/ ，我不确定使用哪个说明符。 这可以用C ++完成吗？

I want to print a float variable x in C++ in the format "1.00e6", where I only want 2 places after the decimal point before the e.

Reading over this: http://www.cplusplus.com/reference/cstdio/printf/, I'm not sure which specifier to use. Can this be done in C++?

最满意答案

您可以在C ++中执行相同的操作：

double f = 1.00e6; std::cout.precision(2); std::cout << std::scientific; std::cout<<f <<std::endl; It will output: 1.00e+06 in this case.

编辑 ：正如@ user657267所指出的，还有一个precision的操纵器，

double f = 1.00e6; std::cout << std::setprecision(2) << std::scientific << f << '\n';

应该有同样的效果。

You can do the same in C++:

double f = 1.00e6; std::cout.precision(2); std::cout << std::scientific; std::cout<<f <<std::endl; It will output: 1.00e+06 in this case.

EDIT: as pointed out by @user657267, There's a manipulator for precision as well,

double f = 1.00e6; std::cout << std::setprecision(2) << std::scientific << f << '\n';

should have same effect.