#, comment

${var}, access value defined in the variable "var"

CMAKE_SOURCE_DIR, the directory that contains the top-level CMakeLists.txt file

CMAKE_CURRENT_SOURCE_DIR, the directory containing the CMakeLists.txt file that is currently being processed

CMAKE_BINARY_DIR, the path to the top level of the build tree

CMAKE_CURRENT_BINARY_DIR, the path to the binary directory currently being processed

PROJECT_SOURCE_DIR, top level source directory for the current project

projectName_SOURCE_DIR, source directory for the named project

PROJECT_BINARY_DIR, top level binary directory for the current project

projectName_BINARY_DIR, binary directory for the named project

CMAKE_C_COMPILER, C compiler

CMAKE_CXX_COMPILTER, C++ compiler

CMAKE_C_FLAGS, C flags

CMAKE_CXX_FLAGS, C++ flags

EXECUTABLE_OUTPUT_PATH, output path for executable program

LIBRARY_OUTPUT_PATH, output path for libraries

CMAKE_BUILD_TYPE, figure out build type, [Debug|Release]

BUILD_SHARED_LIBS, figure out library build model, [OFF|ON]

// main.c
#include <stdio.h>

int main()
{
	printf("Hello World!\n");

	return 0;
}
		

// CMakeLists.txt 1
cmake_minimum_required (VERSION 2.6)
project (Hello)
add_subdirectory(src)
		

// CMakeLists.txt 2
add_executable(Hello main.c)
		

cd build

cmake ..

make, generate executable file "Hello" in build/src

// util.h
#ifndef UTIL_H
#define UTIL_H

void hello();
void world();
void disp();

#endif
		

// hello.c
#include <stdio.h>
#include "util.h"

void hello()
{
	printf("Hello ");
}
		

// util.c
#include <stdio.h>
#include "util.h"

void disp()
{
	hello();
	world();
}
		

// world.c
#include <stdio.h>
#include "util.h"

void world()
{
	printf("World!\n");
}
		

// main.c
#include <util.h>
#include "util.h"

int main()
{
	disp();

	return 0;
}
		

# CMakeLists.txt 1
cmake_minimum_required(VERSION 2.6)

project(c1)

include_directories(${PROJECT_SOURCE_DIR}/include) # add before adding subdirectory
add_subdirectory (src)

add_executable(Hello main.c)
target_link_libraries(Hello mylib)
		

# CMakeLists.txt 2
aux_source_directory(. SRC_LIST)
add_library(mylib ${SRC_LIST})
		

# CMakeLists.txt 1
cmake_minimum_required(VERSION 2.6)

project(c1)

add_subdirectory (src)

add_executable(Hello main.c)
target_include_directories (Hello PUBLIC ${PROJECT_SOURCE_DIR}/include)
target_link_libraries(Hello mylib)
		

# CMakeLists.txt 2
aux_source_directory(. SRC_LIST)
add_library(mylib ${SRC_LIST})
target_include_directories(mylib PUBLIC ${PROJECT_SOURCE_DIR}/include)
		

cd build

cmake ..

make, generate executable file "Hello" in build, generate libmylib.a in build/src

// hello.h
#ifndef HELLO_H
#define HELLO_H

void hello();

#endif
		

// util.h
#ifndef UTIL_H
#define UTIL_H

void disp();

#endif
		

// world.h
#ifndef WORLD_H
#define WORLD_H

void world();

#endif
		

// main.c
#include "util.h"

int main()
{
	disp();

	return 0;
}
		

// util.c
#include <stdio.h>
#include "util.h"
#include "hello.h"
#include "world.h"

void disp()
{
	hello();
	world();
}
		

// hello.c
#include <stdio.h>
#include "hello.h"

void hello()
{
	printf("Hello ");
}
		

// world.c
#include <stdio.h>
#include "world.h"

void world()
{
	printf("World!\n");
}
		

# CMakeLists.txt 1
cmake_minimum_required(VERSION 2.6)

project(c3)

include_directories(${PROJECT_SOURCE_DIR}/include)
add_subdirectory (src)
		

# CMakeLists.txt 2
aux_source_directory(. SRC_LIST)

add_subdirectory(hello)
add_subdirectory(world)

add_executable(Hello.e ${SRC_LIST})
target_link_libraries(Hello.e hello world)
		

# CMakeLists.txt 3
aux_source_directory(. HELLO_LIST)
add_library(hello ${HELLO_LIST})
		

# CMakeLists.txt 4
aux_source_directory(. WORLD_LIST)
add_library(world ${WORLD_LIST})
		

cd build

cmake ..

make, generate executable file "Hello.e" in build/src, generate libhello.a in build/src/hello, generate libworld.a in build/src/world

Code is same as above

// CMakeLists.txt 1
cmake_minimum_required(VERSION 2.6)

project(c3)

include_directories(${PROJECT_SOURCE_DIR}/include)
add_subdirectory (src)
		

// CMakeLists.txt 2
aux_source_directory(. SRC_LIST)

add_subdirectory(hello)
add_subdirectory(world)
add_subdirectory(util)

add_executable(Hello.e ${SRC_LIST})
target_link_libraries(Hello.e util)
		

// CMakeLists.txt 3
aux_source_directory(. UTIL_LIST)

add_library(util ${UTIL_LIST})
target_link_libraries(util hello world)
		

// CMakeLists.txt 4
aux_source_directory(. HELLO_LIST)
add_library(hello ${HELLO_LIST})
		

// CMakeLists.txt 5
aux_source_directory(. WORLD_LIST)
add_library(world ${WORLD_LIST})
		

It is like the code is organized as the following

cmake_minimum_required(VERSION major.minor), set the minimum required version of cmake

project(name, version, language), set a name, version, and enable languages for the entire project

aux_source_directory(dir, var), collects the names of all the source files in the specified directory and stores the list in the "var" provided, "var" should be unique

add_library(libName, [STATIC|SHARED|MODULE], source)

• libName, corresponds to the logical target name and must be globally unique within a project
• STATIC libraries are archives of object files
• SHARED libraries are linked dynamically and loaded at runtime

add_executable(name, source), add an executable to the project using the specified source files

add_subdirectory(dir), add a subdirectory to the build

include_directories(dir), add the given directories to those the compiler uses to search for include files, relative paths are interpreted as relative to the current source directory, affects directory scope, all targets in this CMakeList, as well as those in all subdirectories added after the point of its call

target_include_directories(target, INTERFACE|PUBLIC|PRIVATE, dir), specify include directories or targets to use when compiling a given target

set(variable, value), set a CMake, cache or environment variable to a given value

file(GLOB variable value), GLOB will generate a list of all files that match the globbing expressions and store it into the variable

file(GLOB_RECURSE variable value), traverse all the subdirectories of the matched directory and match the files

find_library(variable libName), this command is used to find a library

target_link_libraries(target libName), specify libraries or flags to use when linking a given target, cmake like to use full path of libraries

message("Code: " ${c_files}), print information

// test.c
#include "util.h"
 
int main()
{
	disp();
 
	return 0;
}
		

# CMakeLists.txt 1
# set up the minimum version of camke
cmake_minimum_required(VERSION 2.6)

# project name
project(c6)

# set up the path for compiled static libraries and dynamic library
set(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/build/lib)
set(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/build/bin)

# figure out the path of header files
include_directories(${PROJECT_SOURCE_DIR}/include)

# figure out the path of compiled libries
link_directories(${PROJECT_SOURCE_DIR}/build/lib)

# add sub directories
add_subdirectory(src)
add_subdirectory(test)

# set up install directory, default is /usr/local
# set(CMAKE_INSTALL_PREFIX ${PROJECT_SOURCE_DIR}/install)

# copy readme.md and license to the install directory
file(COPY ${PROJECT_SOURCE_DIR}/README.md DESTINATION ${CMAKE_INSTALL_PREFIX})
file(COPY ${PROJECT_SOURCE_DIR}/LICENSE DESTINATION ${CMAKE_INSTALL_PREFIX})
		

# CMakeLists.txt 2
# recursive search *.c file and save names to a variable
file(GLOB_RECURSE c_files "*.c")

# turn off MACOSX_RPATH warning
set(CMAKE_MACOSX_RPATH 1)
# create a static library "libhelloworld.a" and a dynamic library "libhelloworld.so"
# dynamic library will be "libhelloworld.dylib" on Mac
add_library(helloworld_lib_shared  SHARED ${c_files})
add_library(helloworld_lib_static STATIC ${c_files})
set_target_properties(helloworld_lib_shared PROPERTIES OUTPUT_NAME "helloworld")
set_target_properties(helloworld_lib_static PROPERTIES OUTPUT_NAME "helloworld")
set_target_properties(helloworld_lib_shared PROPERTIES VERSION 1.2 SOVERSION 1)

# create an executable program
add_executable(Hello.e main.c)
target_link_libraries(Hello.e helloworld)

# install executable program to folder "bin" in the install directory
# install dynamic library to folder "lib" in the install directory
# install static library to folder "lib" in the install directory
INSTALL(TARGETS Hello.e helloworld_lib_shared helloworld_lib_static
	RUNTIME DESTINATION bin
     	LIBRARY DESTINATION lib
     	ARCHIVE DESTINATION lib)

# install header files to folder "include" in the install directory
INSTALL(DIRECTORY ${PROJECT_SOURCE_DIR}/include/ DESTINATION include)
		

# CMakeLists.txt 3
# recursively find *.c files
file(GLOB_RECURSE c_files *.c)
# print out a list of source files
message("test code: " ${c_files})

# create executable test program
add_executable(mytest ${c_files})
target_link_libraries(mytest helloworld)

# install executable test program to folder "bin" in the install directory
INSTALL(TARGETS mytest
	RUNTIME DESTINATION bin)
		

cd build

cmake ..

make, generate executable files in build/src, generate libraries in build/lib

make install, install executable programs to inallPath/bin, install libraries to installPath/lib, install header files to installPath/include

How to collect source files with CMake without globbing?

• If no CMakeLists.txt file changes when a source is added or removed then the generated build system cannot know when to ask CMake to regenerate
• Use GLOB, "touch CMakeLists.txt", let cmake know new source files have been added

Install to a different directory

• cmake -DCMAKE_INSTALL_PREFIX=path ..
• make
• make install

• Where is the source code, figure out project folder
• Where to build binaries, figure out build folder
• Configure, make create variable available
• Generate, genreate makefile

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