Cmake uses the basic grammar of basic knowledge I

One ．cmake Predefined variables in

PROJECT_SOURCE_DIR    The root directory of the project 
PROJECT_BINARY_DIR    function cmake Directory of commands , Usually ${PROJECT_SOURCE_DIR}/build
CMAKE_INCLUDE_PATH    environment variable 
CMAKE_LIBRARY_PATH    environment variable 
CMAKE_CURRENT_SOURCE_DIR       What is being processed CMakeLists.txt Path 
CMAKE_CURRENT_BINARY_DIR      target Compile Directory 
CMAKE_CURRENT_LIST_FILE        The output calls the variable CMakeList.txt Full path to 
CMAKE_CURRENT_LIST_LINE        Output the line of the variable 
CMAKE_MODULE_PATH              Define your own cmake The path of the module 
EXECUTABLE_OUTPUT_PATH         Redefine the storage location of the target binary executable 
LIBRARY_OUTPUT_PATH            Redefine the storage location of the target link library file 
PROJECT_NAME                   Back to pass PROJECT The name of the project defined by the directive 

Two ． system information

1.
CMAKE_MAJOR_VERSION
CMAKE_MINOR_VERSION
CMAKE_PATCH_VERSION
2.
CMAKE_SYSTEM            System name , Such as linux-2.6.22
CMAKE_SYSTEM_NAME       System name without version , Such as linux
CMAKE_SYSTEM_VERSION    Such as ：2.6.22
CMAKE_SYSTEM_PROCESSOR  Processor name , Such as i686

3、 ... and ． Switch options
BUILD_SHARED_LIBS Control the default library compilation method , If present and true, This will result in all libraries being built as shared libraries , Unless the library is explicitly added as a static library . This variable is usually used as OPTION Add to the project , So that each user of the project can decide whether to use shared libraries or static libraries to build the project .

CMAKE_C_FLAGS         Set up C Compilation options 
CMAKE_CXX_FLAGS       Set up C++ Compilation options 

Four ． Basic grammar rules
1.cmake Variable usage ${} Method value , But in IF The variable name is used directly in the control statement
2. Instructions ( Parameters 1 Parameters 2)
Parameters use parentheses , Parameters are separated by spaces or semicolons
3. Instructions are case independent , Parameters and variables are case dependent .

5、 ... and ． List of some common commands

1.PROJECT
   Specify project name 
2.SET
   Defining variables 
3.MESSAGE
   Output user-defined information or variable values to the terminal 
  STATUS
  WARNING
  AUTHOR_WARNING
  FATAL_ERROR  error , Terminate all processes 
  SEND_ERROR   error , Carry on , However, the generation step will be skipped 
4.ADD_EXECUTABLE
   Generate executable files 
5.ADD_LIBRARY
   Generate dynamic or static libraries 
6.SET_TARGET_PROPERTIES
 Set the name of the output , Set the version and of the dynamic library API edition 
7.CMAKE_MINIMUM_REQUIRED
   Statement CMake Version requirements for 
8.ADD_SUBDIRECTORY
   Add a subdirectory to the current project where the source files are stored , And you can specify the storage location of intermediate binary and target binary .
  ADD_SUBDIRECTORY(src_dir  [binary_dir]  [EXCLUDE_FROM_ALL])
  EXCLUDE_FROM_ALL Indicates that this directory is excluded from the compilation process .
9.INCLUDE_DIRECTORIES
   Add multiple specific header file search paths to the project 
10.LINK_DIRECTORIES
    Add non-standard search paths for shared libraries 
11.TARGET_LINK_LIBRARIES
    by target Add a shared library that needs to be connected 
12.ADD_DEFINITIONS
   towards C/C++ Compiler added -D Definition 
13.ADD_DEPENDENCIES
   Definition target Other dependent target, Make sure target Before building , It depends on target It's built .
14.AUX_SOURCE_DIRECTORY
   AUX_SOURCE_DIRECTORY(dir VAR)
    Find all source code files in a directory and store the list in a variable 
15.INCLUDE
  INCLUDE(file [OPTIONAL]) Used to load CMakeLists.txt
16.FIND_
  FIND_FILE(<VAR> name path1 path2 ...)
  VAR The variable represents the full path of the file found , Include file name 
  FIND_LIBRARY(<VAR> name path1 path2 ...)
  VAR The variable represents the full path of the library found , Contains the library file name 
  
17.IF
  IF(expression)
  IF(not exp)
  IF(var1 AND var2)
  IF(var1 OR var2)
  IF(COMMAND cmd)
  IF(EXISTS dir)
  IF(file1 IS_NEWER_THAN file2)
  IF(DEFINED var)
  IF(var MATCHES regex)
  
18. Number comparison expressions 
IF(variable LESS number)
IF(string LESS number)
IF(variable GREATER number)
IF(string GREATER number)
IF(variable EQUAL number)
IF(string EQUAL number)

19. Compare in alphabetical order 
IF(variable STRLESS number)
IF(string STRLESS number)
IF(variable STRGREATER number)
IF(string STRGREATER number)
IF(variable STREQUAL number)
IF(string STREQUAL number)

20.WHILE
  WHILE(condition)
COMMAND(ARGS ...)
COMMAND(ARGS ...)
  ENDWHILE(condition)

21.FOREACH
  FOREACH(loop_var arg1 arg2 ...)
COMMAND(ARGS ...)
COMMAND(ARGS ...)
  ENDFOREACH(loop_var)

22.LIST usage 
  list(LENGTH <list><output variable>)
  list(GET <list> <elementindex> [<element index> ...]<output variable>)
  list(APPEND <list><element> [<element> ...])
  list(FIND <list> <value><output variable>)
  list(INSERT <list><element_index> <element> [<element> ...])
  list(REMOVE_ITEM <list> <value>[<value> ...])
  list(REMOVE_AT <list><index> [<index> ...])
  list(REMOVE_DUPLICATES <list>)
  list(REVERSE <list>)
  list(SORT <list>)

LENGTH　　　　   　　　　  return list The length of 
GET　　　　　　    　　　　 return list in index Of element To value in 
APPEND　　　　    　　　　 Add new element To list in 
FIND　　　　　　   　　　　 return list in element Of index, No return found -1
INSERT 　　　　　　　　　  Will be new element Insert into list in index The location of 
REMOVE_ITEM　　　　　　   from list Delete a element
REMOVE_AT　　　　　　　   from list Delete the specified index Of element
REMOVE_DUPLICATES       from list Delete duplicate element
REVERSE 　　　　　　　　   take list Content reversal of 
SORT 　　　　　　　　　　  take list Sort alphabetically 

6、 ... and ． common problem

1.cmake How to generate dynamic and static libraries in 
ADD_LIBRARY and SET_TARGET_PROPERTIES
2.cmake How to use dynamic and static libraries in 
  INCLUDE_DIRECTORIES, LINK_DIRECTORIES, TARGET_LINK_LIBRARIES
3.cmake How to specify the output path of the generated file 
    Use SET Command redefine ECECUTABLE_OUTPUT_PATH and LIBRARY_OUTPUT_PATH Variable to specify the location of the final binary file .
4.cmake How to add compilation options in 
  CMAKE_C_FLAGS
  CMAKE_CXX_FLAGS
   Use ADD_DEFINITION add to 
5.cmake How to add header file path in 
  INCLUDE_DIRECTORIES
6.cmake How to assign values to variables in 
  SET
  AUX_SOURCE_DIRECTORY
7. Specify installation path 
CMake Variable ``CMAKE_INSTALL_PREFIX'' Used to determine the installation location of files . If you use cmake --install You can customize the installation directory through --prefix Parameter assignment . For multi configuration tools , Please use --config Parameter assignment 
 configuration .