A link to info on 'function pointers'

Using Arduino Programming Questions
4

I cleaned up your code a bit. One of the reasons things weren't printing was that you were mixing printf with Serial.print.

Modified version:

typedef void (* myFunctionPointer) ();

/**
 * Using a function pointer in a structure.
 */
typedef struct myObject {
  myFunctionPointer functionPointer;
  int value;
};

/**
 * Passing a function pointer to a function.
 */
void passFunction(myFunctionPointer functionPointer) ;

void passFunction(myFunctionPointer functionPointer) {
  /* call our passed function */
  functionPointer();
}

void testFunction() {
  Serial.println("hello");
}

void testFunction2() {
  Serial.println("juhu");
}

myFunctionPointer functionPointers[2];

void setup() {
  Serial.begin(115200);

  /* pointer to void function with no parameters myFunction */
  myFunctionPointer functionPointer = testFunction;
  
  /* call original function */
  Serial.print("#1 ");
  testFunction();
  
  /* call our new pointer function */
  Serial.print("#2 ");
  functionPointer();

  /* create struct */
  myObject Object;
  Object.value = 1;
  Object.functionPointer = testFunction;

  Serial.print("#3 ");
  Serial.println(Object.value);
  Serial.print("#4 ");
  Object.functionPointer();


  functionPointers[0] = testFunction;
  Serial.print("#5 ");
  Serial.println((int) functionPointers[0]);

  functionPointers[1] = testFunction2;
  Serial.println((int) functionPointers[1]);

  /* Creepy! but possible. */
  Serial.print("#6 ");
  functionPointers[0] ();
  Serial.print("#7 ");
  functionPointers[1] ();

}

void loop() {
  // put your main code here, to run repeatedly: 
}

Output:

#1 hello
#2 hello
#3 1
#4 hello
#5 103
96
#6 hello
#7 juhu