C++动态链接库实践

朱雀 2023-08-17 16:30 133阅读 0赞

参考：[https://www.cnblogs.com/Anker/p/3746802.html][https_www.cnblogs.com_Anker_p_3746802.html]

gcc -fPIC -shared calc.c -o libcalc.so， 编译得到

![1444224-20190831082928754-372069685.png][]

在linux上 man dlopen可以得到以下信息：

![1444224-20190831083216659-2034812336.png][]

头文件注释：

![1444224-20190831091010137-1506806703.png][]

实践内容：

#include <stdio.h>
    #include <stdlib.h>
    #include <dlfcn.h>
    
    //动态链接库路径
    #define LIB_CACULATE_PATH "/home/dahui/work/workspace/CStudy/src/libcalc.so"
    
    //函数指针
    typedef int (*CAC_FUNC)(int, int);
    
    int main(void) {
    
        printf("!!!Hello World!!!\n"); /* prints !!!Hello World!!! */
    
        void *handle;
        char *error;
        CAC_FUNC cac_func = NULL;
    
        //打开动态链接库
        handle = dlopen(LIB_CACULATE_PATH, RTLD_LAZY);
        if (!handle) {
            fprintf(stderr, "%s\n", dlerror());
            exit(EXIT_FAILURE);
        }
    
        //清除之前存在的错误
        dlerror();
    
        //获取一个函数
        *(void **) (&cac_func) = dlsym(handle, "add");
        //cac_func = (CAC_FUNC) dlsym(handle, "add");
        if ((error = dlerror()) != NULL) {
            fprintf(stderr, "%s\n", error);
            exit(EXIT_FAILURE);
        }
        printf("add: %d\n", (*cac_func)(2, 7));
    
        cac_func = (CAC_FUNC) dlsym(handle, "sub");
        printf("sub: %d\n", cac_func(9, 2));
    
        cac_func = (CAC_FUNC) dlsym(handle, "mul");
        printf("mul: %d\n", cac_func(3, 2));
    
        cac_func = (CAC_FUNC) dlsym(handle, "div");
        printf("div: %d\n", cac_func(8, 2));
    
        printf("!!!Hello World!!!"); /* prints !!!Hello World!!! */
    
        //关闭动态链接库
        dlclose(handle);
        //exit(EXIT_SUCCESS);
    
        printf("!!!Hello World!!!"); /* prints !!!Hello World!!! */
    
        return EXIT_SUCCESS;
    }

输出：

![1444224-20190902075329298-284771609.png][]

转载于:https://www.cnblogs.com/do-your-best/p/11437836.html

[https_www.cnblogs.com_Anker_p_3746802.html]: https://www.cnblogs.com/Anker/p/3746802.html
[1444224-20190831082928754-372069685.png]: /images/20230810/a69e84198bf34c4aa11713aca240866e.png
[1444224-20190831083216659-2034812336.png]: /images/20230810/cf3ef76b256f47f68aa8f132dd8e3e3e.png
[1444224-20190831091010137-1506806703.png]: /images/20230810/cc2366e21e3d49f586f8c35a6f25d93b.png
[1444224-20190902075329298-284771609.png]: /images/20230810/db3766cdcbc34698a457b8899032df6f.png