There are often some requirements for output, such as left alignment, right alignment, floating-point output, vertex output and so on. Many default output formats can not meet the requirements of programmers, so it is necessary to process the output data and output it in a certain format.

It is called I/O stream format control in C++, which is equivalent to format output in C.

In C++, the header file is iomanip, which contains some keywords to control the format and align the output left and right. Right-aligned output; Dec, decimal output, oct, octal output, hex, hexadecimal output16; Fixed output in floating-point form