1

Hello! first of all sorry for my english, is not my native language.

Im making a small memory game and im getting problems when i make the buttons. The problem is that i cannot change the text in the buttons and i want them empty and when you press one of them, show the text

using UnityEngine;
using System.Collections;

public class CardsManager : MonoBehaviour 
{
	private string[] cards;
	private string[] romaji; // romaji characters
	private string[] hiragana; // hiragana characters
	private string[] katakana; //katakana characters

	//The cards for the game
	float card1;
	float card2;
	float card3;
	float card4;
	float card5;
	float card6;
	float card7;
	float card8;

	void Start () 
	{

				//Romaji characters
				romaji = new string[] {
			"a", "i", "u", "e", "o", };

				//Hiragana characters
				hiragana = new string[] {
			"あ", "い", "う", "え", "お", };

		GenerateCards ();

	}

	void Update ()
	{

	}

	void OnGUI () 
	{
		//Make the gui of 480*800
		float scaleX = (float)(Screen.width) / 480.0f;
		float scaleY = (float)(Screen.height) / 800.0f;
		GUI.matrix = Matrix4x4.TRS(new Vector3(0, 0, 0), Quaternion.identity, new Vector3(scaleX, scaleY, 1));
		
		int temp = 0;
		string empty = "";
		
		for(int x = 0; x <= 3; x++)
		{
			for(int y = 0; y <= 3; y++)
			{
				if(GUI.Button(new Rect(25 + (110 * x),250 + (110 * y), 100, 100), "" + cards[temp++]))
				{

				}
			}
		}
	}

	void GenerateCards ()
	{
		card1 = Random.Range (0, 113);
		card2 = Random.Range (0, 113);
		card3 = Random.Range (0, 113);
		card4 = Random.Range (0, 113);
		card5 = Random.Range (0, 113);
		card6 = Random.Range (0, 113);
		card7 = Random.Range (0, 113);
		card8 = Random.Range (0, 113);

		cards = new string[] {
			hiragana[(int)card1], 
			hiragana[(int)card2], 
			hiragana[(int)card3], 
			hiragana[(int)card4], 
			hiragana[(int)card5],
			hiragana[(int)card6],
			hiragana[(int)card7],
			hiragana[(int)card8],
			romaji[(int)card1],
			romaji[(int)card2], 
			romaji[(int)card3],
			romaji[(int)card4],
			romaji[(int)card5],
			romaji[(int)card6],
			romaji[(int)card7],
			romaji[(int)card8]};
		
		//Knuth shuffle algorithm
		for (int x= 0; x < 15; x++)
		{
			string temp = cards[x];
			int random = Random.Range(x, 15);
			cards[x] = cards[random];
			cards[random] = temp;
		}
	}
}

well, the strings are much longer but i dont consider relevant put every character inside of them here. I hope someone can help me or show me some links where i can find a solution.

Also im getting the error NullReferenceException: Object reference not set to an instance of an object and i dooooooont really know why, if someone can help with this too i’ll be grateful.

2

First, about null reference exception. Your arrays “romaji” and “hiragama” have length 5, but you try access in function GenerateCards() at index much more 5. Random.Range(0, 113) return int value from 0 to 112. Second, as I understand, text of button is not visible before button is pressed. In your case, create array for showing text:

 private bool[] cardsShow = null; //create boolean array for showing cards

 void GenerateCards () {
  //Simple way, not use all variables card1 and etc, create loop
  cards = new string[16]; //count 16 from your code
  cardsShow = new bool[16]; //allocate our array
  for(int i = 0; i < cards.Length/2; i++) {
   card1 = Random.Range (0, hiragana.Length); //not 113, length hiragana and romaji shall be match
   cards *= hiragana[card1];*

cards[i + cards.Length/2] = romaji[card1];
//Initialization bool array
cardsShow = false;
cardsShow[i + cards.Length/2] = false;
}
//Knuth shuffle algorithm
for (int x= 0; x < 15; x++) { //maybe replace “15” on “cards.Length-1”?
string temp = cards[x];
int random = Random.Range(x, 15);
cards[x] = cards[random];
cards[random] = temp;
}
}
void OnGUI () {
//Make the gui of 480*800
float scaleX = (float)(Screen.width) / 480.0f;
float scaleY = (float)(Screen.height) / 800.0f;
GUI.matrix = Matrix4x4.TRS(new Vector3(0, 0, 0), Quaternion.identity, new Vector3(scaleX, scaleY, 1));

//int temp = 0; //no need to use this variable
string empty = “”;
for(int x = 0; x <= 3; x++) {
for(int y = 0; y <= 3; y++) {
//Use cardsShow for showing text
if(GUI.Button(new Rect(25 + (110 * x),250 + (110 * y), 100, 100), (cardsShow[4x+y]?cards[4x+y]:“”))) {
cardsShow[4*x+y] = true;
}
}
}
}
I hope that it will help you.