C compilation error "called object is not a function or function pointer" [closed]

Function declarations

A modern function declaration in C will at least specify

• the return value type or void
• the name
• argument types with their (optional) names or void

The specification of extern binding is implied for function declarations. The return value is missing (which is acceptable until C23) but the comma after the void parameter specification is syntactically wrong.

Preprocessor macros

In your example, MY_CODE is defined but doesn't have a text to be replaced with (which can be used to branch in the preprocessor for creating code variants). So will have a hard time to use it productively between a comma and a closing parenthesis in C. You may, on the other hand, include also commas into macro definitions.

Function pointers (as arguments)

From your comment on the accepted answer, I read that you are trying to call a function with a function pointer as an argument. Function pointers look a bit complicated, so they are often made more accessible via typedef:

/* translate1: pointer to a function that takes and returns a char */
char (*translate1)(char);

/* translate_function_t is a name for above function type 
   translate2 is again a pointer to a function that takes and returns a char
*/
typedef char (*translate_function_t)(char);
translate_function_t translate2;

/* transliterate: replaces each char in str by calling your_translate */
void transliterate(char* str, translate_function_t your_translate);

The transliterate function in the above example takes function pointer arguments in the second parameter your_translate.

Simple function pointer example

#include <stdio.h>

/* translate_function_t: pointer to a function that takes and returns a char */
typedef char (*translate_t)(char);

/* transliterate: replaces each char in str by calling translate */
void transliterate(char* str, translate_t translate);

char my_trans(char a)
{
    if (a == 'x')
        return 'u';
    if (a == 'u')
        return 'x';
    return a;
}

void transliterate(char* str, translate_t translate)
{
    while (*str) {
        *str = translate(*str);
        str++;
    }
}

int main()
{
    char msg[] = "Hello world! (xu)";
    printf("%s\n", msg);
    transliterate(msg, my_trans);
    printf("%s\n", msg);
    return 0;
}