Learn camke to compile for large projects
Preliminary knowledge:
1. Linux basic commands: such as ls, cd, vim, apt or yum (different download programs are used in different Linux systems), cat, etc.
2. Linux download cmake (usually comes with it)
3. The process of c/c++ forming an executable file
1. A single source file (like cmake)
Method one:
gcc -o main main.c
Law 2:
g++ -o main main.cpp
Method three:
step1: Write a .cpp file and put it in an empty folder
step2: Write CMakeLists.txt under this folder
#CMakeLists.txt
PROJECT(HELLO)
SET(SRC_LIST main.cpp)
MESSAGE(STATUS "This is BINARY dir" ${HELLO_SOURCE_DIR})
MESSAGE(STATUS "This is BINARY dir" ${HELLO_BINARY_DIR})
ADD_EXECUTABLE(hello ${SRC_LIST})step3: Use cmake to generate makefille files
cmake . cmake at current location (generates makeflie file)
Generated file:
step4 Compile makeflie at the current file location
makeGenerate executable file main
step5 Execute the executable file
./main-----------------------------------------------------
Introduction to cmake syntax:
#CMakeLists.txt
PROJECT(HELLO)
SET(SRC_LIST main.cpp)
MESSAGE(STATUS "This is BINARY dir" ${HELLO_SOURCE_DIR})
MESSAGE(STATUS "This is BINARY dir" ${HELLO_BINARY_DIR})
ADD_EXECUTABLE(hello ${SRC_LIST})The PROJECT keyword is used to specify the name of the project and the supported languages, all languages are supported by default .
PROJECT (HELLO) specifies the project name as HELLO
PROJECT (HELLO CXX) project name is HELLO and supports c++
PROJECT (HELLO C CXX) project name is HELLO and supports c and c++
This specification implicitly defines two cmake variable tips: <projectname> is the project name
<projectname>_BINARY_DIR in this case HELLO_BINARY_DIR
<projectname>_SOURCCE_DIR in this case HELLO_SOURCE_DIR
The MESSAGE keyword can be used directly. These two variables currently point to the current working directory, and we will talk about external compilation later.
If the project name is changed, these two variable names will also change
Two predefined variables PROJECT_BINARY_DIR and PROJECT_SOURCCE_DIR These two variables are consistent with HELLO_SOURCE_DIR HELLO_BINARY_DIR
SET keyword
used to display the specified variable
SET(SRC-LIST main.cpp ) The SRC_LIST variable contains main.cpp
Can also be SET(SRC_LIST main.cpp t1.cpp t2.cpp)
MESSAGE keywords
Output custom information to the terminal
Contains three
SEND_ERROR generated an error and the build process was skipped
SATUS outputs prefix-unique information
FATAL_ERROR terminates all cmake processes immediately
For example, this keyword in this example will output
ADD_EXECUTABLE keyword
generate executable
ADD_EXECUTABLE(hello ${SRC_LIST}) Generate an executable file named hello The source file reads the contents of the variable SRC_LIST and can also be directly written as ADD_EXECUTABLE(hello main.cpp)
The above example can be simplified to:
PROJECT(HELLO)
ADD_EXECUTABLE(hello main.cpp)
Note that the project name HELLO has nothing to do with the executable file name hello
Basic Principles of Grammar
Variables use ${} to take values, but in the IF statement, the variable name is used directly
Instructions (parameter 1, parameter 2...) parameters use brackets to expand the parameters and separate them with spaces and semicolons. Take ADD_EXECUTABLE(hello main.cpp) as an example
Instructions are case-insensitive and variable parameters are case-sensitive
Recommend all caps
grammar attention
SET(SRC_LIST main.cpp) can be written as SET(SRC_LIST "main.cpp") If the file name has spaces, "" must be added
ADD_EXECUTABLE(hello main) suffix can not be written, it will automatically search for .c .cpp, try not to write like this
Built Inside and Built Outside
The above-mentioned temporary files generated for internal components are inconvenient to clean up,
The external build is to put the cmake generated file into the build folder for easy recompilation
2.