Question

When a function can take another function as a parameter, how can type-checking occur?

(Programming languages)

Answer 1

You cannot pass function to another function as parameter. But, you can pass function reference to another function using function pointers. Using function pointer you can store reference of a function and can pass it to another function as normal pointer variable.

When you pass as a pointer that you need to declare the type of function in parameter itself.

#include <stdio.h>


/* Function declarations */
void greetMorning();
void greeEvening();
void greetNight();

void greet(void (*greeter)());



int main()
{
    // Pass pointer to greetMorning function 
    greet(greetMorning);


    // Pass pointer to greetEvening function 
    greet(greeEvening);


    // Pass pointer to greetNight function 
    greet(greetNight);


    return 0;
}


/**
 * Function to print greeting message.
 * 
 * @greeter     Function pointer that can point to functions
 *              with no return type and no parameters.
 */
void greet(void (*greeter)())
{
    // Call greeter function pointer
    greeter();
}



void greetMorning() 
{
    printf("Good, morning!\n");
}


void greeEvening() 
{
    printf("Good, evening!\n");
}


void greetNight() 
{
    printf("Good, night!\n");
}

Output