Basic-What is compile unit?

When a C or CPP file is being compiled, the Preprocessor first recursively contains the header file to form a single source file containing all necessary information. This source file is a compilation unit. This compilation unit will be compiled into a target file (. O or. OBJ) with the same name as the CPP file name ). Connection ProgramLink the symbols generated in different compilation units to form an executable program.

Files after preprocessing (this is a temporary file in the memory)
# Include is expanded during preprocessing, and the same is true for macros.

A expanded. cpp file is a compilation unit.

One XX. H (preprocessing) + one XX. cpp = one compilation unit
A compilation unit (Compiled) = XX. OBJ
Add multiple. OBJ files of the entire program (connected) =. EXE (executable files)