CMake入門-02-HelloWorld擴展

工作環境

• 系統：macOS Mojave 10.14.6
• CMake: Version 3.15.0-rc4

Hello,World! 擴展-同一目錄，多個源文件

(1) 新建 hello 目錄，創建文件 CMakeLists.txt、main.cpp、MathFunctions.h、MathFunctions.cpp

$ mkdir hello
$ cd hello
$ touch CMakeLists.txt main.cpp MathFunctions.h MathFunctions.cpp
$ ll
-rw-r--r--  1 staff  staff   124B  8 14 17:19 CMakeLists.txt
-rw-r--r--  1 staff  staff     0B  8 15 16:22 MathFunctions.cpp
-rw-r--r--  1 staff  staff     0B  8 15 16:22 MathFunctions.h
-rw-r--r--@ 1 staff  staff   145B  8 14 21:33 main.cpp

(2) 編寫 MathFunctions.h

int power(int base, int exponent);

(3) 編寫 MathFunctions.cpp

#include <stdio.h>
#include <stdlib.h>
#include "MathFunctions.h"

int power(int base, int exponent) {
    int result = base;
    int i;

    if (exponent == 0) {
        return 1;
    }

    for(i = 1; i < exponent; ++i){
        result = result * base;
    }
    return result;
}

(4) 編寫 main.cpp

#include <iostream>
#include "MathFunctions.h"

using namespace std;

int main(int argc, char const *argv[]) {
  /* code */
  // cout << "Hello,World!" << power(2, 3) << endl;
  printf("%s power(2,3)=%d \n", "Hello,World!", power(2, 3));
  return 0;
}

(5) 編寫 CMakeLists.txt

# CMake 最低版本號要求
cmake_minimum_required(VERSION 3.15.0)

# 項目名
project(hello)

# 查找當前目錄下的所有源文件，並將名稱保存到 SRC_LIST 變量
# set(SRC_LIST main.cpp MathFunctions.h MathFunctions.cpp)
aux_source_directory(. SRC_LIST)

# 指定生成目標
add_executable(hello ${SRC_LIST})

(6) 編譯運行

$ mkdir build
$ cd build
$ pwd
/Users/staff/Desktop/hello/build

$ cmake ..
-- The C compiler identification is AppleClang 10.0.1.10010046
-- The CXX compiler identification is AppleClang 10.0.1.10010046
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/staff/Desktop/hello/build

$ make
Scanning dependencies of target hello
[ 33%] Building CXX object CMakeFiles/hello.dir/MathFunctions.cpp.o
[ 66%] Building CXX object CMakeFiles/hello.dir/main.cpp.o
[100%] Linking CXX executable hello
[100%] Built target hello

$ ./hello
Hello,World! power(2,3)=8

Hello,World! 擴展-多個目錄，多個源文件

(1) 新建 hello 目錄，創建文件 CMakeLists.txt、main.cpp、math/MathFunctions.h、math/MathFunctions.cpp

$ mkdir hello
$ cd hello
$ mkdir math
$ touch CMakeLists.txt main.cpp math/MathFunctions.h math/MathFunctions.cpp
$ tree
.
├── CMakeLists.txt
├── main.cpp
└── math
    ├── MathFunctions.cpp
    └── MathFunctions.h

(2) 編寫代碼

• math/MathFunctions.h

int power(int base, int exponent);

• math/MathFunctions.cpp

#include <stdio.h>
#include <stdlib.h>
#include "MathFunctions.h"

int power(int base, int exponent) {
    int result = base;
    int i;

    if (exponent == 0) {
        return 1;
    }

    for(i = 1; i < exponent; ++i){
        result = result * base;
    }
    return result;
}

• main.cpp

#include <iostream>
// 這裏要加上 math 目錄
#include "math/MathFunctions.h"

using namespace std;

int main(int argc, char const *argv[]) {
  /* code */
  // cout << "Hello,World!" << power(2, 3) << endl;
  printf("%s power(2,3)=%d \n", "Hello,World!", power(2, 3));
  return 0;
}

• CMakeLists.txt

# CMake 最低版本號要求
cmake_minimum_required(VERSION 3.15.0)

# 項目名
project(hello)

# 查找當前目錄下的所有源文件，並將名稱保存到 SRC_LIST 變量
aux_source_directory(. SRC_LIST)
# 查找 math 目錄下的所有源文件，並將名稱保存到 MATH_SRC_LIST 變量
aux_source_directory(${PROJECT_SOURCE_DIR}/math MATH_SRC_LIST)

# 指定生成目標
add_executable(hello ${SRC_LIST} ${MATH_SRC_LIST})

(3) 再多學一點

由於多了 math 目錄，我們看到 main.cpp 中，#include "math/MathFunctions.h" 也要加上目錄。

如果我們不想加 math 目錄，直接 #include "MathFunctions.h"，操作如下：

• main.cpp

#include <iostream>
// 這裏去掉 math 目錄
#include "MathFunctions.h"

using namespace std;

int main(int argc, char const *argv[]) {
  /* code */
  // cout << "Hello,World!" << power(2, 3) << endl;
  printf("%s power(2,3)=%d \n", "Hello,World!", power(2, 3));
  return 0;
}

• CMakeLists.txt 添加 include_directories

# CMake 最低版本號要求
cmake_minimum_required(VERSION 3.15.0)

# 項目名
project(hello)

# 查找當前目錄下的所有源文件，並將名稱保存到 SRC_LIST 變量
aux_source_directory(. SRC_LIST)
# 查找 math 目錄下的所有源文件，並將名稱保存到 MATH_SRC_LIST 變量
aux_source_directory(${PROJECT_SOURCE_DIR}/math MATH_SRC_LIST)

# 添加頭文件路徑
include_directories(${PROJECT_SOURCE_DIR}/math)

# 指定生成目標
add_executable(hello ${SRC_LIST} ${MATH_SRC_LIST})

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相關參考：
CMake 官方網站
CMake 多個源文件-多個目錄

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