CMake

CMake is a versatile tool that helps you build C/C++ projects on just about any platform you can think of.

Running CMake does not build your software. You typically need to run makefile

Main Options

cmake [options] -S <path-to-directory-where-root-CMakeLists.txt-file-is> -B <path-to-build>

Example C++

Working Example

gt.sandbox.checkout.commit.cleanly b22d565 \
&& cd "$GT_SANDBOX_REPO/cpp/hello-world" \
&& cmake -S . -B ./build \
&& cd build \
&& make \
&& ./HelloWorldProjectName.executable

HelloWorld Example CMakeLists.txt

HelloWorldExample CMakeLists.txt

# Min versin cmake check
cmake_minimum_required(VERSION 3.0)
 
# Project name
project(HelloWorldProjectName)
 
# Add executable target ${PROJECT_NAME}.executable will be the
# name of the executable.
add_executable(${PROJECT_NAME}.executable hello_world_main.cpp)

---

Command to reproduce:

gt.sandbox.checkout.commit 65d00c5 \
&& cd "${GT_SANDBOX_REPO}/cpp/hello-world" \
&& cmd.run.announce "cmake -S . -B ./build && cd build && make && ./HelloWorldProjectName.executable"

Recorded output of command:

-- Configuring done
-- Generating done
-- Build files have been written to: /Users/vintrin/git_repos/glassthought-sandbox/cpp/hello-world/build
[100%] Built target HelloWorldProjectName.executable
Hello World!

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Relationships

• relies-on:CMakeListsTxt
• cmake-generates-your-makefile:makefile

Files Generates by CMake

Files Generates by CMake Video Ref Timestamp

Don’t modify files generated by CMake within your ./build path directory. Instead modify: CMakeListsTxt.

Example Files Generated By CMake

mac> cd "$GT_SANDBOX_REPO/cpp/hello-world/build" && tree
.
├── CMakeCache.txt
├── CMakeFiles
│   ├── 3.25.2
│   │   ├── CMakeCCompiler.cmake
│   │   ├── CMakeCXXCompiler.cmake
│   │   ├── CMakeDetermineCompilerABI_C.bin
│   │   ├── CMakeDetermineCompilerABI_CXX.bin
│   │   ├── CMakeSystem.cmake
│   │   ├── CompilerIdC
│   │   │   ├── CMakeCCompilerId.c
│   │   │   ├── CMakeCCompilerId.o
│   │   │   └── tmp
│   │   └── CompilerIdCXX
│   │       ├── CMakeCXXCompilerId.cpp
│   │       ├── CMakeCXXCompilerId.o
│   │       └── tmp
│   ├── CMakeDirectoryInformation.cmake
│   ├── CMakeError.log
│   ├── CMakeOutput.log
│   ├── CMakeScratch
│   ├── HelloWorldProjectName.executable.dir
│   │   ├── DependInfo.cmake
│   │   ├── build.make
│   │   ├── cmake_clean.cmake
│   │   ├── compiler_depend.make
│   │   ├── compiler_depend.ts
│   │   ├── depend.make
│   │   ├── flags.make
│   │   ├── link.txt
│   │   └── progress.make
│   ├── Makefile.cmake
│   ├── Makefile2
│   ├── TargetDirectories.txt
│   ├── cmake.check_cache
│   ├── pkgRedirects
│   └── progress.marks
├── Makefile
└── cmake_install.cmake
 
10 directories, 29 files

Reference

• CMake Tutorial EP 1 | Understanding The Basics
• how-to-build-a-cmake-based-project

More in depth

Using CMake to install into user level bin directory.

Installing into User Level Bin Directory cmake install

About

cmake install

Allows installation of your executable into widely accessible bin folders such as /usr/local/bin/

Live example using “cmake install”

gt.sandbox.checkout.commit.cleanly 56ae6c2 \
&& cd cpp/trim \
&& (rm -rf ./build; rm /usr/local/bin/trim-example-app; echo "cleaned") \
&& cmake -S . -B ./build \
&& cd build \
&& make install \
&& trim-example-app first second

Sample CMake file with install

Sample CMake with installation

 
cmake_minimum_required(VERSION 3.0.0)
 
project(TrimProjectName)
 
add_executable(trim-example-app main.cpp)
 
# Just running make will not install the executable.
# You need to run
#
# make install
#
# DESTINATION bin will be written to some system defined directory
# on MAC for me it ended up in
# -- Installing: /usr/local/bin/trim-example-app
install(TARGETS trim-example-app DESTINATION bin)

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Using libraries with CMake

Usage of Libraries with CMake

Links

• add_library documentation
• CMake Tutorial - Libraries Video Timestamp

Command in CMake

add_library

add_library(<name> [STATIC | SHARED | MODULE]
            [EXCLUDE_FROM_ALL]
            [<source>...])

add_library documentation

Example CMakeLists.txt for library

CMakeLists.txt

cmake_minimum_required(VERSION 3.0)
 
project(mymath)
 
add_library(mymath adder.cpp)

Working Example

Working Example

gt.sandbox.checkout.commit.cleanly 9671ea2 \
&& cd "$GT_SANDBOX_REPO/cpp/LibProducer" \
&& cmake -S . -B ./build \
&& cd build \
&& make \
&& cd "$GT_SANDBOX_REPO/cpp/LibConsumer" \
&& cmake -S . -B ./build \
&& cd build \
&& make \
&& echo "Running ./LibConsumer" \
&& ./LibConsumer

Output of building library

...
[ 50%] Building CXX object CMakeFiles/mymath.dir/adder.cpp.o
[100%] Linking CXX static library libmymath.a
[100%] Built target mymath

note lib prefix is added and .a suffix is added.

The default output of add_library is static library of .a.

dot-a will contain the definitions. But will still need the declaration (the header file).

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