mirror of
https://github.com/ttroy50/cmake-examples.git
synced 2025-12-18 20:24:35 +03:00
117 lines
5.9 KiB
Markdown
117 lines
5.9 KiB
Markdown
# Hello CMake
|
|
|
|
Shows a hello world example, which uses a seperate cpp file and include directory.
|
|
|
|
## New Concepts
|
|
|
|
### Directory Paths
|
|
|
|
CMake syntax specifies a number of variables which can be used to help find useful directories in your project or source tree. Some of these include
|
|
|
|
Variable | Info
|
|
-------- | ------
|
|
CMAKE_SOURCE_DIR | The root source directory
|
|
CMAKE_CURRENT_SOURCE_DIR | The current source directory if using sub-projects and directories
|
|
PROJECT_SOURCE_DIR | The source director of the current cmake project.
|
|
CMAKE_BINARY_DIR | The root binary / build directory. This is the directory you run the cmake command from
|
|
CMAKE_CURRENT_BINARY_DIR | The build directory you are currently in.
|
|
PROJECT_BINARY_DIR | The build directory for the current project.
|
|
|
|
### Including Directories
|
|
|
|
```
|
|
include_directories(
|
|
${PROJECT_SOURCE_DIR}/inc
|
|
)
|
|
```
|
|
|
|
When you have a seperate include folders, you can include them using the 'include_directories' function.
|
|
This will add these directories to the compiler with the -I flag, e.g. -I/directory/path
|
|
|
|
### Setting Source files
|
|
|
|
```
|
|
# Create a sources variable with a link to all cpp files to compile
|
|
set(SOURCES
|
|
src/Hello.cpp
|
|
src/main.cpp
|
|
)
|
|
|
|
add_executable(${PROJECT_NAME} ${SOURCES})
|
|
```
|
|
|
|
Creating a variable which includes the source files allows you to be clearer about these files and add them to various commands, for example, the 'add_executable()' function.
|
|
|
|
An alternative to setting specific file names in the SOURCES variable is to use a GLOB command to find files using wildcard pattern matching.
|
|
|
|
```
|
|
file(GLOB SOURCES "src/*.cpp")
|
|
```
|
|
|
|
## Building the example
|
|
|
|
```
|
|
$ mkdir build
|
|
|
|
$ cd build
|
|
|
|
$ cmake ..
|
|
-- The C compiler identification is GNU 4.8.4
|
|
-- The CXX compiler identification is GNU 4.8.4
|
|
-- Check for working C compiler: /usr/bin/cc
|
|
-- Check for working C compiler: /usr/bin/cc -- works
|
|
-- Detecting C compiler ABI info
|
|
-- Detecting C compiler ABI info - done
|
|
-- Check for working CXX compiler: /usr/bin/c++
|
|
-- Check for working CXX compiler: /usr/bin/c++ -- works
|
|
-- Detecting CXX compiler ABI info
|
|
-- Detecting CXX compiler ABI info - done
|
|
-- Configuring done
|
|
-- Generating done
|
|
-- Build files have been written to: /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build
|
|
|
|
$ make
|
|
Scanning dependencies of target hello_headers
|
|
[ 50%] Building CXX object CMakeFiles/hello_headers.dir/src/Hello.cpp.o
|
|
[100%] Building CXX object CMakeFiles/hello_headers.dir/src/main.cpp.o
|
|
Linking CXX executable hello_headers
|
|
[100%] Built target hello_headers
|
|
|
|
$ ./hello_headers
|
|
Hello Headers!
|
|
```
|
|
|
|
### Verbose Output
|
|
|
|
In the previous examples, when running the make command the output only shows the status of the build. To see the full output for debugging purposes you can add 'VERBOSE=1' to the command to show all commands.
|
|
|
|
The VERBOSE output is show below, and looking at the output lets you see the include directories being added to the g++ command.
|
|
|
|
```
|
|
$ make clean
|
|
$ make VERBOSE=1
|
|
/usr/bin/cmake -H/home/matrim/workspace/cmake-examples/01-basic/hello_headers -B/home/matrim/workspace/cmake-examples/01-basic/hello_headers/build --check-build-system CMakeFiles/Makefile.cmake 0
|
|
/usr/bin/cmake -E cmake_progress_start /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build/CMakeFiles /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build/CMakeFiles/progress.marks
|
|
make -f CMakeFiles/Makefile2 all
|
|
make[1]: Entering directory `/home/matrim/workspace/cmake-examples/01-basic/hello_headers/build'
|
|
make -f CMakeFiles/hello_headers.dir/build.make CMakeFiles/hello_headers.dir/depend
|
|
make[2]: Entering directory `/home/matrim/workspace/cmake-examples/01-basic/hello_headers/build'
|
|
cd /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build && /usr/bin/cmake -E cmake_depends "Unix Makefiles" /home/matrim/workspace/cmake-examples/01-basic/hello_headers /home/matrim/workspace/cmake-examples/01-basic/hello_headers /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build/CMakeFiles/hello_headers.dir/DependInfo.cmake --color=
|
|
make[2]: Leaving directory `/home/matrim/workspace/cmake-examples/01-basic/hello_headers/build'
|
|
make -f CMakeFiles/hello_headers.dir/build.make CMakeFiles/hello_headers.dir/build
|
|
make[2]: Entering directory `/home/matrim/workspace/cmake-examples/01-basic/hello_headers/build'
|
|
/usr/bin/cmake -E cmake_progress_report /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build/CMakeFiles 1
|
|
[ 50%] Building CXX object CMakeFiles/hello_headers.dir/src/Hello.cpp.o
|
|
/usr/bin/c++ -I/home/matrim/workspace/cmake-examples/01-basic/hello_headers/inc -o CMakeFiles/hello_headers.dir/src/Hello.cpp.o -c /home/matrim/workspace/cmake-examples/01-basic/hello_headers/src/Hello.cpp
|
|
/usr/bin/cmake -E cmake_progress_report /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build/CMakeFiles 2
|
|
[100%] Building CXX object CMakeFiles/hello_headers.dir/src/main.cpp.o
|
|
/usr/bin/c++ -I/home/matrim/workspace/cmake-examples/01-basic/hello_headers/inc -o CMakeFiles/hello_headers.dir/src/main.cpp.o -c /home/matrim/workspace/cmake-examples/01-basic/hello_headers/src/main.cpp
|
|
Linking CXX executable hello_headers
|
|
/usr/bin/cmake -E cmake_link_script CMakeFiles/hello_headers.dir/link.txt --verbose=1
|
|
/usr/bin/c++ CMakeFiles/hello_headers.dir/src/Hello.cpp.o CMakeFiles/hello_headers.dir/src/main.cpp.o -o hello_headers -rdynamic
|
|
make[2]: Leaving directory `/home/matrim/workspace/cmake-examples/01-basic/hello_headers/build'
|
|
/usr/bin/cmake -E cmake_progress_report /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build/CMakeFiles 1 2
|
|
[100%] Built target hello_headers
|
|
make[1]: Leaving directory `/home/matrim/workspace/cmake-examples/01-basic/hello_headers/build'
|
|
/usr/bin/cmake -E cmake_progress_start /home/matrim/workspace/cmake-examples/01-basic/hello_headers/build/CMakeFiles 0
|
|
``` |