Select header file type

The header files in C ++ can be defined as. h and. HPP.

. H files can generally have Data Type Definitions and function declarations. The HPP file can contain data types, function declarations, and function definitions.

When using HPP, you must note that the error Link 2005 error is reported when multiple files reference HPP. The reason is that the compiler will compile the included header file when compiling the CPP file. HPP has defined functions in the file and will also be compiled into the OBJ file. If other CPP also calls this HPP file, the functions in the HPP file will be compiled into multiple OBJ files, the compiler does not report an error during compilation, but a link error occurs when obj is generated for an EXE file.

In this case, use. h instead.