Clean Build Directory using CMake

When working with CMake, keeping the build directory clean is important to avoid stale or conflicting object files, especially when switching build configurations. Instead of manually deleting the build directory or its contents, CMake provides convenient ways to clean up the build artifacts safely. This tutorial demonstrates how to clean build directory using CMake.

Let's say we have a minimal CMake project in the CMakeLists.txt file:

cmake_minimum_required(VERSION 3.27)
project(myapp)
 
set(CMAKE_CXX_STANDARD 17)
 
add_executable(${PROJECT_NAME} main.cpp)

Run the following command to generate the necessary build files before starting the build:

cmake -S . -B build

Next, you can build the project by running:

cmake --build build

Sometimes, you want to clean out all generated build files before rebuilding. CMake provides two useful options for this:

• Clean build directory

You can clean the build directory by running:

cmake --build build -t clean

This tells the build system to run its clean target, which deletes all compiled files and intermediate objects but keeps the generated build files (like Makefile or project files).

After cleaning, you can rebuild as usual:

cmake --build build

• Clean first before building

Alternatively, you can use the --clean-first option:

cmake --build build --clean-first

This will first clean the build directory (like the previous command) and then immediately build the project in one step.