cmake --build .
The meaning of this command is: Execute the build system in the current directory to generate build targets.
A brief description of the cmake project construction process:
1. First, use the command line: 'cmake <source tree>', for example: cmake .., the project file project files are generated in your build directory (external build method), which is also called build tree/binary tree in official documents , which includes, for example: Makefile, and some other related files/directories/subdirectories;
2. Secondly, it is natural to compile and build the generated project (project files), using what you said 'cmake --build .'
3. Finally, the '.' behind --build refers to the path of the generated build tree. Generally speaking, if you know exactly which builder (build generator) you are using in your system, For example: Unix Makefiles, you can use make directly to build projects.
For this form of --build, it is mostly used in automated scripts, or in the IDE environment.
Note: <source tree> refers to the path where the source file + top-level CMakeLists are located, cmake .. assumes that the path is at the upper level.
After the Makefile is created through the cmake ./cmake .. command, the make command is generally used to compile the file. The cmake --build here has the same effect as make
Why not make directly, but use the cmake --build command, mainly for cross-platform, after using this form, no matter what generator you use, CMake can build correctly, otherwise if you use Ninja or other generators, then make will not take effect