dlopen实例

  关于函数的介绍,概念性的东东,自己看man
 

[root@kenthy study]# cat dlopen.c
#include <stdio.h>
#include <stdlib.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());
     exit(1);
   }

   dlerror(); /* Clear any existing error */
   cosine = dlsym(handle, "cos");
   if ((error = dlerror()) != NULL) {
     fprintf (stderr, "%s\n", error);
     exit(1);
    }

    printf ("%f\n", (*cosine)(0));
    dlclose(handle);
    return 0;
  }
[root@kenthy study]# gcc -Wall -o dlopen dlopen.c -ldl
[root@kenthy study]# ./dlopen
1.000000