Cmake

CMake Mastery

CMake is the most popular build system generator for C++. It generates platform-specific build files from simple configuration files.

Basic CMake Project

MyProject/
├── CMakeLists.txt
├── main.cpp
└── include/
    └── utils.h

Minimal CMakeLists.txt

cmake_minimum_required(VERSION 3.10)
project(MyProject)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_executable(myapp main.cpp)

Building

mkdir build
cd build
cmake ..
make
./myapp

Variables

# Set variable
set(MY_VAR "value")

# Use variable
${MY_VAR}

# List
set(SOURCES main.cpp util.cpp helper.cpp)

# Cache variables
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")

Multiple Source Files

cmake_minimum_required(VERSION 3.10)
project(MyProject)

set(CMAKE_CXX_STANDARD 17)

# Collect all .cpp files automatically
file(GLOB SOURCES "src/*.cpp")

add_executable(myapp ${SOURCES})

Headers and Include Directories

include_directories(${CMAKE_SOURCE_DIR}/include)

add_executable(myapp
    main.cpp
    src/util.cpp
    src/helper.cpp
)

Targets-Based Commands (Modern CMake)

add_executable(myapp main.cpp)

target_include_directories(myapp PRIVATE ${CMAKE_SOURCE_DIR}/include)

target_compile_features(myapp PRIVATE cxx_std_17)

Libraries

# Static library
add_library(mylib STATIC src/lib.cpp)

# Shared library
add_library(myshared SHARED src/lib.cpp)

# Link library
add_executable(myapp main.cpp)
target_link_libraries(myapp mylib)

Finding Packages

# Find a package
find_package(Threads REQUIRED)

# Use package
add_executable(myapp main.cpp)
target_link_libraries(myapp Threads::Threads)

Common Packages

# Boost
find_package(Boost REQUIRED)
target_link_libraries(myapp Boost::filesystem)

# OpenSSL
find_package(OpenSSL REQUIRED)
target_link_libraries(myapp OpenSSL::SSL OpenSSL::Crypto)

# Threads
find_package(Threads REQUIRED)
target_link_libraries(myapp Threads::Threads)

Options

option(ENABLE_TESTS "Enable unit tests" ON)
option(USE_OPENGL "Use OpenGL rendering" OFF)

if(ENABLE_TESTS)
    enable_testing()
    add_subdirectory(tests)
endif()

Complete Example

cmake_minimum_required(VERSION 3.16)
project(MyApp VERSION 1.0.0)

# C++ Standard
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# Output directories
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)

# Find packages
find_package(Threads REQUIRED)

# Source files
file(GLOB SOURCES
    ${CMAKE_SOURCE_DIR}/src/*.cpp
)

# Create executable
add_executable(myapp ${SOURCES})

# Include directories
target_include_directories(myapp
    PRIVATE ${CMAKE_SOURCE_DIR}/include
)

# Link libraries
target_link_libraries(myapp
    Threads::Threads
)

# Install rules
install(TARGETS myapp
    RUNTIME DESTINATION bin
)

Best Practices

1. Use modern CMake (3.10+)
2. Prefer target_ commands over global commands*
3. Use VERSION in project()
4. Set C++ standard explicitly
5. Use out-of-source builds

Key Takeaways

• CMake generates build files from CMakeLists.txt
• Use target_* commands for better organization
• find_package locates external libraries
• Always use out-of-source builds

Next Steps

Now let’s learn about testing in C++.

Next Chapter: 11_testing/52_unit_testing.md - Unit Testing with Google Test