CMake 引用第三方库

一、cmake简介

cmake 是gnu工具链中构建项目重要的一环，而且在windows、linux、OS X中都可以使用，特别是linux C/C++程序员必备基本功。

二、基本命令：

命名变量：

SET(INC_DIR /usr/local/include)

SET(LINK_DIR /usr/local/lib)

SET(SOURCE_FILES main.cpp)

包含目录：相当于 -I

include_directories(${INC_DIR})

链接库目录：相当于 -L

link_directoried(${LINK_DIR})

引用库：需要放在 ADD_EXECUTABLE 后

target_link_libraries(target pthread cjson)

生成目标：

ADD_EXECUTABLE(main ${SOURCE_FILES})

三、例子:

使用cjson第三方库，cjson 已编译在 /usr/local/cjson 目录下。

1.示例代码：

#include 
#include 
#include "cjson/cJSON.h"

char *create_monitor(void)
{
    const unsigned int resolution_numbers[3][2] = {
        {1280, 720},
        {1920, 1080},
        {3840, 2160}
    };
    char *string = NULL;
    cJSON *name = NULL;
    cJSON *resolutions = NULL;
    cJSON *resolution = NULL;
    cJSON *width = NULL;
    cJSON *height = NULL;
    size_t index = 0;

    cJSON *monitor = cJSON_CreateObject();
    if (monitor == NULL)
    {
        goto end;
    }

    name = cJSON_CreateString("Awesome 4K");
    if (name == NULL)
    {
        goto end;
    }
    /* after creation was successful, immediately add it to the monitor,
     * thereby transferring ownership of the pointer to it */
    cJSON_AddItemToObject(monitor, "name", name);

    resolutions = cJSON_CreateArray();
    if (resolutions == NULL)
    {
        goto end;
    }
    cJSON_AddItemToObject(monitor, "resolutions", resolutions);

    for (index = 0; index < (sizeof(resolution_numbers) / (2 * sizeof(int))); ++index)
    {
        resolution = cJSON_CreateObject();
        if (resolution == NULL)
        {
            goto end;
        }
        cJSON_AddItemToArray(resolutions, resolution);

        width = cJSON_CreateNumber(resolution_numbers[index][0]);
        if (width == NULL)
        {
            goto end;
        }
        cJSON_AddItemToObject(resolution, "width", width);

        height = cJSON_CreateNumber(resolution_numbers[index][1]);
        if (height == NULL)
        {
            goto end;
        }
        cJSON_AddItemToObject(resolution, "height", height);
    }

    string = cJSON_Print(monitor);
    if (string == NULL)
    {
        fprintf(stderr, "Failed to print monitor.\n");
    }

end:
    cJSON_Delete(monitor);
    return string;
}


int main(){
    char* str = create_monitor();
    if ( str != NULL ){
        printf("%s\n",str);
    }
    return 0;
}

2.CMakeLists.txt文件内容：

PROJECT (test)
CMAKE_MINIMUM_REQUIRED(VERSION 2.8)

set(INC_DIR /usr/local/cjson/include)
set(LINK_DIR /usr/local/cjson/lib)

include_directories(${INC_DIR})
link_directories(${LINK_DIR})

ADD_EXECUTABLE(main main.c)

target_link_libraries(main cjson)

3.编译运行

mkdir build && cd build && cmake .. && make 

./main