C - dynamic function call

Question

I have a testing file with tests defined as

static int test1(){
    /*some tests here*/
    return 0;
}
static int test2(){
    /*some tests here*/
    return 0;
}
/*...etc*/`

and I was wondering if there's a way to call all of the tests in a loop, instead of writing the call for each one. (There are some functions I need to call before and after each test, and with >20 tests, this might get really annoying. I've also just been curious about doing things like this for a while.)

I was thinking something similar to:

int main(){
    int (*test)() = NULL;
    for(i = 1; i <= numtests; i++){
      /*stuff before test*/
      (*test)();
      /*stuff after test*/
    }
    return 0;
}

but I'm not sure how to proceed with using the value of "i" to set the test pointer.

Answer 1

You can use a self inclusion trick to get a list of function pointers:

#ifndef LIST_TESTS
#define TEST(name, ...) static int name() __VA_ARGS__

/* all includes go here */
#endif // ifndef LIST_TESTS

TEST(test1, {
  /* some tests here */
  return 0;
})

TEST(test2, {
  /* some tests here */
  return 0;
})

#undef TEST

#ifndef LIST_TESTS
int main(void) {
  int (*tests[])() = {
    #define LIST_TESTS
    #define TEST(name, ...) name,
    #include __FILE__
  };
  int num_tests = sizeof(tests) / sizeof(tests[0]);
  int i;

  for (i = 0; i < num_tests; ++i) {
    /* stuff before test */
    (tests[i])();
    /* stuff after test */
  }

  return 0;
}
#endif // ifndef LIST_TESTS

Answer 2

On linux

put the functions in a separate shared library (.so). Then use dlopen to open it and dlsym to get a function pointer by its name

On windows

put the functions in a separate dll (basically the same thing). Then use LoadLibrary to open it and GetProcAddress to get a pointer to the function

A lot more typing that you wanted to do , but it will let you do what you want

Answer 3

What you can do is define an array of function pointers with all your functions and then loop in all elements of the array.

int (*array[])(void) = {test1, test2, test3};