C/C++教程

CMake语法—流程控制(if-foreach-while)

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目录
  • CMake语法—流程控制(if-foreach-while)
    • 1.流程控制
      • 1.1 代码结构
      • 1.2 示例代码
      • 1.3 运行结果
      • 1.4 小结

CMake语法—流程控制(if-foreach-while)

1.流程控制

1.1 代码结构

目录结构

  • learn_cmake:为根目录
  • build:为CMake配置输出目录(在此例中即生成sln解决方案的地方)
  • cmake_config.bat:执行CMake配置过程的脚本(双击直接运行)
  • CMakeLists.txt:CMake脚本

1.2 示例代码

  1. 示例代码(CMakeLists.txt文件内容)

    cmake_minimum_required(VERSION 3.18)
    
    # 设置工程名称
    set(PROJECT_NAME KAIZEN)
    
    # 设置工程版本号
    set(PROJECT_VERSION "1.0.0.10" CACHE STRING "默认版本号")
    
    # 工程定义
    project(${PROJECT_NAME}
        LANGUAGES CXX C
        VERSION ${PROJECT_VERSION}
    )
    
    # 打印开始日志
    message(STATUS "\n########## BEGIN_TEST_PROCESS_CONTROL")
    
    # if example
    set(var_3 "camke")
    
    if (DEFINED var_1)
        message("defined var_1")
    elseif (DEFINED var_2)
        message("defined var_2")
    elseif (DEFINED var_3)
        message("defined var_3")
    else()
        message("defined nothing")
    endif()
    
    # endif
    
    ## foreach example
    
    set(var_list "C++" "JAVA" Python "CMake" 1024)
    
    foreach(item ${var_list})
         message("当前变量是:${item}")
    endforeach()
    
    set(result 0)
    set(end 0)
    
    foreach(element RANGE 0 100)
        math(EXPR result "${result} + ${element}")
        if (result LESS 100)
            continue()   ## continue
        endif()
        if (result GREATER 1000)
            set(end ${element})
            break()    ## break
        endif()
    endforeach()
    
    message("from 0 plus to ${end} is : ${result}")
    
    ## endforeach
    
    ### while example
    
    set(var_max 5)
    
    while(${var_max} GREATER 0)
        message(${var_max})
        math(EXPR var_max "${var_max} - 1")
    endwhile()
    
    ### endwhile
    
    # 打印结束日志
    message(STATUS "########## END_TEST_PROCESS_CONTROL\n")
    
    
  2. cmake_config.bat

    @echo off
    set currentDir=%~dp0
    set buildDir=%currentDir%
    set cmakeOutputDir=%currentDir%\build
    cmake -S %buildDir% -B %cmakeOutputDir% -G"Visual Studio 16 2019" -T v140 -A x64
    pause
    

1.3 运行结果

  1. 本地环境

    本地安装VS版本:Visual Studio 2019(2015工具集)

    CMake版本:3.18.2

    F:\learn_cmake
    λ cmake --version
    cmake version 3.18.2
     
    CMake suite maintained and supported by Kitware (kitware.com/cmake).
    
  2. 输出结果

    -- Selecting Windows SDK version 10.0.18362.0 to target Windows 10.0.17763.
    -- The CXX compiler identification is MSVC 19.0.24245.0
    -- The C compiler identification is MSVC 19.0.24245.0
    -- Detecting CXX compiler ABI info
    -- Detecting CXX compiler ABI info - done
    -- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/amd64/cl.exe - skipped
    -- Detecting CXX compile features
    -- Detecting CXX compile features - done
    -- Detecting C compiler ABI info
    -- Detecting C compiler ABI info - done
    -- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/amd64/cl.exe - skipped
    -- Detecting C compile features
    -- Detecting C compile features - done
    --
    ########## BEGIN_TEST_PROCESS_CONTROL
    defined var_3
    当前变量是:C++
    当前变量是:JAVA
    当前变量是:Python
    当前变量是:CMake
    当前变量是:1024
    from 0 plus to 45 is : 1035
    5
    4
    3
    2
    1
    -- ########## END_TEST_PROCESS_CONTROL
    
    -- Configuring done
    -- Generating done
    -- Build files have been written to: F:/learn_cmake/build
    请按任意键继续. . .
    

1.4 小结

  1. if 概要

    if(<condition>)
        <commands>
    elseif(<condition>) # optional block, can be repeated
        <commands>
    else()              # optional block
        <commands>
    endif()
    

    具体可参考最钟情官方文档:https://cmake.org/cmake/help/latest/command/if.html

  2. foreach 概要

    foreach(<loop_var> <items>)
        <commands>
    endforeach()
    

    具体可参考最钟情官方文档:https://cmake.org/cmake/help/latest/command/foreach.html

  3. while 概要

    while(<condition>)
        <commands>
    endwhile()
    

    具体看参考最钟情官方文档:https://cmake.org/cmake/help/latest/command/while.html

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