#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>


void say_hi() {
    printf("Hi\n");
}


void say_bye() {
    printf("Bye\n");
}


// say_something(…) takes the address of a function as its sole parameter.
// The name of the parameter is 'say_fn'.  'say_fn' must be a function that
// returns void and takes no parameters.
void say_something(void(*say_fn)()) {
//                 ▼       ▼     └───> types of parameters that say_fn takes
//  «type fn returns»  «name of parameter»

    // Call the function that was passed to say_something(…)
    say_fn();
}


int main(int argc, char* argv[]) {
    say_something( say_hi );   // say_hi is the address of the say_hi(…) function.
    say_something( say_bye );  // say_bye is the address of the say_bye(…) function.
    
    return EXIT_SUCCESS;
}
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