I found this great code to pick a random number from a "hat" without repeat:

/* RandomHat
  Paul Badger 2007 - updated for Teensy compile 2017
  choose one from a hat of n consecutive choices each time through loop
  Choose each number exactly once before reseting and choosing again
*/

#define randomHatStartNum 0  // starting number in hat
#define randomHatEndNum 25    // ending number in hat - end has to be larger than start  
#define numberInHat (randomHatEndNum - randomHatStartNum) + 1

void setup()
{
  Serial.begin(9600);
  Serial.println("start ");
}

void loop()
{ // randomHat test
  for (int i = 1; i <= numberInHat; i++) {
    int x = randomHat();
    Serial.print(x);
    Serial.print(", ");
    delay(50);
  }
  Serial.println(" ");
}

int randomHat() {
  int thePick;    //this is the return variable with the random number from the pool
  int theIndex;
  static int currentNumInHat = 0;
  static int randArray[numberInHat];

  if  (currentNumInHat == 0) {                  // hat is emply - all have been choosen - fill up array again
    for (int i = 0 ; i < numberInHat; i++) {    // Put 1 TO numberInHat in array - starting at address 0.
      if (randomHatStartNum < randomHatEndNum) {
        randArray[i] = randomHatStartNum + i;
      }
    }
    currentNumInHat = abs(randomHatEndNum - randomHatStartNum) + 1;   // reset current Number in Hat
    Serial.print(" hat is empty ");
    // if something should happen when the hat is empty do it here
  }

  theIndex = random(currentNumInHat);                  //choose a random index from number in hat
  thePick = randArray[theIndex];
  randArray[theIndex] =  randArray[currentNumInHat - 1]; // copy the last element in the array into the the empty slot
  //                                                     // as the the draw is random this works fine, and is faster
  //                                                     // the previous version. - from a reader suggestion on this page
  currentNumInHat--;    // decrement number in hat
  return thePick;
}

I would like to use a custom array to choose from like so:

char *things[]={
"Thing 1", 
"Thing 2", 
"Thing 3", 
"Thing 4", 
"Thing 5", 
"Thing 6", 
};

Which is quite possible as I use the numbers from to first piece of code to select items from my custom array.

So I have two questions about this:

The first being the code first returns "hat is empty" before the numbers.

start
  hat is empty 11, 24, 17, .......
  hat is empty 4, 19, 23, .......

Is there a way to reverse this?

And secondly, I would like define the randomHatEndNum automatic by the lenght of my custom array, but I have trouble implementing that code. What is the right way to approach this?