Below is a simple example of C function pointers.

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

typedef int (*functionptr)(int x, int y);

int add(int x, int y);
int mult(int x, int y);

int main(void) {
	functionptr f1 = add;
	functionptr f2 = mult;

	printf("f(5,5,) = %d\n", f1(5, 5));
	printf("f(5,5,) = %d\n", f2(5, 5));

	return 0;
}

int add(int x, int y) {
	return x + y;
}

int mult(int x, int y) {
	return x * y;
}