Executable
$ cmake [options] (<path-to-source> | <path-to-existing-build>)
Assuming that the directory contains
.
├── CMakeLists.txt
└── main.cpp
#include <iostream>
using namespace std;
int main () {
cout << "Hello world" << endl;
return 0;
}
The minimal CMakeLists.txt
file contains
cmake_minimum_required (VERSION 2.6)
project(Hello)
add_executable(${PROJECT_NAME} main.cpp)
Running cmake .
creates a Makefile
in the same directory whose recipes are cross platform commands, CMake’s documentation suggest that the build is separated from the source
$ mkdir build
$ cd build
$ cmake ..
Running the default target in the makefile creates the executable Hello
, note that this is done on the ./build/
directory
$ make
Scanning dependencies of target Hello
[ 50%] Building CXX object CMakeFiles/Hello.dir/main.cc.o
[100%] Linking CXX executable Hello
[100%] Built target Hello
$ ./Hello
Hello world
set(<variable> <value>)
sets a normal variable available to the current function or directory scope, variables can be accessed with${variable}
project(<PROJECT-NAME> [LANGUAGES] [<language-name>...])
, sets the following variablesPROJECT_NAME
, same as<PROJECT-NAME>
PROJECT_SOURCE_DIR
same as/path/to/project/
PROJECT_BINARY_DIR
same as/path/to/project/build/
add_executable(<name> source1 [source2 ...])
adds an executable target calledname
to be built from the source files listed
Useful variables
CMAKE_SOURCE_DIR
- path to the top level of the source tree (default value./
)CMAKE_BINARY_DIR
- path to the top level of the build tree (default value./build/
)CMAKE_RUNTIME_OUTPUT_DIRECTORY
- path to the executable (usually set to${CMAKE_BINARY_DIR}/bin/
)CMAKE_ARCHIVE_OUTPUT_DIRECTORY
- path to the static libraries (code from static libraries is included in the executable, usually set to${CMAKE_BINARY_DIR}/lib/
)CMAKE_LIBRARY_OUTPUT_DIRECTORY
- path to the shared libraries (additional code required by the executable, usually set to${CMAKE_BINARY_DIR}/lib/
)
Project structure and organization
. project
├── build
├── include
│ └── project
│ └── World.hpp
└── src
├── World.cpp
└── main.cpp
The CMakeLists.txt
file should do the following
- add the
./include
path to compiler include search path - create an executable file from
main.cpp
into./build/bin/
- create an static/dynamic library (in the example is
World.cpp
) into./build/lib/
- link the library with the executable
cmake_minimum_required(VERSION 3.0)
project(runner)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin")
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")
# the -I flag in gcc
include_directories(
${PROJECT_SOURCE_DIR}/include/
)
set(APP_SOURCES src/main.cpp)
set(LIB_SOURCES src/World.cpp)
# creates ./build/bin/runner
add_executable(${PROJECT_NAME} ${APP_SOURCES})
# shared library
set(LIBRARY_NAME World)
add_library(${LIBRARY_NAME} SHARED ${LIB_SOURCES})
target_link_libraries(${PROJECT_NAME} ${LIBRARY_NAME})
include_directories(dir)
- add the given directories to those the compiler uses to search for include files (gcc-I dir
)add_library(library_name [STATIC | SHARED | MODULE] source1 [source2...])
- adds a library calledlibrary_name
to be built from the source files listedSTATIC
- archives of object files.a
(archive)SHARED
- libraries dynamically linked at runtime.so
(shared object)
target_link_libraries(target item)
, specify libraries/flags to use when linking a given target
Complex CMake configuration
A complex CMake configuration will have multiple CMakeLists.txt
files per directory
./CMakeLists.txt
- configures dependencies, platform specifics and output paths./src/CMakeLists.txt
- configures the library to build