这两个就是格式控制的~ostream成员函数里面的，也可以用输出流操作符来控制，都一样的~附给你一些看看~

其中cout.setf跟setiosflags一样的，cout.precision跟setprecision一样~

#include <iomanip>

这里面iomanip的作用比较多:

主要是对cin,cout之类的一些操纵运算子，比如setfill,setw,setbase,setprecision等等。它是I/O流控制头文

件,就像C里面的格式化输出一样.-These two formats is controlled- the ostream member function inside, can also be used to control the output stream operator, are attached to the same ~ ~ wherein cout.setf you look at some of the same with setiosflags, cout.precision like setprecision ~#include <iomanip> There are more iomanip role: mainly for cin, cout like some manipulation operators, such setfill, setw, setbase, setprecision like. It is the I/O flow control header, formatted as an output C of the same inside.