引自：http://linux.about.com/library/cmd/blcmdl3_dlsym.htm

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

int main(int argc, char **argv) {
    void *handle;
    double (*cosine)(double);
    char *error;

    handle = dlopen ("libm.so", RTLD_LAZY);
    if (!handle) {
        fprintf (stderr, "%s\n", dlerror());
        return 1;
    }
    cosine = dlsym(handle, "cos");
    if ((error = dlerror()) != NULL)  {
        fprintf (stderr, "%s\n", error);
        return 1;
    }
    printf ("%f\n", (*cosine)(2.0));
    dlclose(handle);
    return 0;
}

编译命令如下：

   gcc -rdynamic -o foo foo.c -ldl