1.函数集合

#include <dlfcn.h>

void *dlopen(const char *filename, int flag);
char *dlerror(void);
void *dlsym(void *handle, const char *symbol);
int dlclose(void *handle);

Link with -ldl.

 

2.Demo例子

caculate.c用于编译成一个库

int add(int a,int b)
{
    return (a + b);
}

int sub(int a, int b)
{
    return (a - b);
}

int mul(int a, int b)
{
    return (a * b);
}

int div(int a, int b)
{
    return (a / b);
}

View Code

main.c调用这个库里面的函数

#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>


#define LIB_CACULATE_PATH "./libcaculate.so"

typedef int (*CAC_FUNC)(int, int);

int main()
{
    void *handle;
    char *error;
    CAC_FUNC cac_func = NULL;

    handle = dlopen(LIB_CACULATE_PATH, RTLD_LAZY);
    if (!handle) {
        fprintf(stderr, "%s\n", dlerror());
        return -1;
    }

    //获取一个函数
    cac_func = dlsym(handle, "add");
    if ((error = dlerror()) != NULL)  {
        fprintf(stderr, "%s\n", error);
        return -1;
    }
    printf("add: 2+7=%d\n", cac_func(2,7));

    cac_func = dlsym(handle, "sub");
    printf("sub: 9-2=%d\n", cac_func(9,2));

    cac_func = dlsym(handle, "mul");
    printf("mul: 3*2=%d\n", cac_func(3,2));

    cac_func = dlsym(handle, "div");
    printf("div: 8/2=%d\n", cac_func(8,2));

    dlclose(handle);

    return 0;
}

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编译执行：

编译：
$ gcc -rdynamic -o main main.c -ldl
$ gcc -shared -fPIC caculate.c -o libcaculate.so
执行：
$ ./main 
add: 2+7=9
sub: 9-2=7
mul: 3*2=6
div: 8/2=4

View Code

 

3.详细信息：# man dlopen