C# Instances share same values - class

Question

programming student here, quite new to what i am about to ask but i'm sure you people will know. I have to make a game where several pictureboxes are created using an array. I also have to make a class that has a health variable of 5. When you click on one of the pictureboxes, its health has to go down by 1. I am as far as this, but the problem is that the health variable is shared by all pictureboxes, where in reality I want every picturebox to have it's own health.
This is my code:
public partial class Form1 : Form
{
Invader monster; // Invader is the name of the class
Random rand = new Random();
PictureBox[] pb = new PictureBox[5];
private void Spawner()
{
for (int i = 0; i < 5; i++)
{
this.monster = new Invader();
this.pb[i] = new PictureBox();
this.pb[i].Name = "pb" + i.ToString();
this.pb[i].Location = new Point(rand.Next(10, 300), monster.LocY);
this.pb[i].BackgroundImageLayout = ImageLayout.Stretch;
this.pb[i].BackgroundImage = Image.FromFile(#"Path");
this.pb[i].BackColor = Color.Transparent;
this.pb[i].Size = new System.Drawing.Size(40, 30);
this.Controls.Add(this.pb[i]);
this.pb[i].Click += this.Form1_Click;
}
}
private void Form1_Click(object sender, EventArgs e)
{
PictureBox currentpicturebox = (PictureBox)sender;
this.monster.HealthDown();
if (this.monster.Health == 0)
{
currentpicturebox.Dispose();
}
}
and my class:
class Invader
{
// Fields
private int health;
// Properties
public int Health
{
get { return this.health; }
}
// Constructor
public Invader()
{
this.health = 5;
}
// Methods
public void HealthDown()
{
this.health -= 1;
}
Lets say i click 1 picture box 4 times, and click another one 1 time. With this code the picturebox last clicked on will be disposed. Any ideas on how to fix this?

Answer 1

Your Invader monster is an instance variable of Form1 and in your method Spawner() inside the for loop you are reassigning it again every time: this.monster = new Invader();
Basically when you click on a picturebox (isn't different what) in your Form1_Click method happen that is everytime your last monster istance that get it's health down and not the supposed one.
In order to fix this you can:
transform monster in an array of Invader object instead of an Invader object, the number of elements must be the same as the number of pictureboxes
foreach picturebox assign as a Tag the index of the corrispondent Invader on the monster array
Here an example:
public partial class Form1 : Form
{
// EDIT - Become an array
Invader[] monster = new Invader[5]; // Invader is the name of the class
Random rand = new Random();
PictureBox[] pb = new PictureBox[5];
private void Spawner()
{
for (int i = 0; i < 5; i++)
{
this.monster[i] = new Invader(); // EDIT
this.pb[i] = new PictureBox();
this.pb[i].Name = "pb" + i.ToString();
this.pb[i].Location = new Point(rand.Next(10, 300), monster.LocY);
this.pb[i].BackgroundImageLayout = ImageLayout.Stretch;
this.pb[i].BackgroundImage = Image.FromFile(#"Path");
this.pb[i].BackColor = Color.Transparent;
this.pb[i].Size = new System.Drawing.Size(40, 30);
this.Controls.Add(this.pb[i]);
this.pb[i].Click += this.Form1_Click;
this.pb[i].Tag = i; // EDIT - Added tag assignation
}
}
private void Form1_Click(object sender, EventArgs e)
{
PictureBox currentpicturebox = (PictureBox)sender;
this.monster[(int)currentpicturebox.Tag].HealthDown(); // EDIT
if (this.monster[(int)currentpicturebox.Tag].Health == 0) //EDIT
{
currentpicturebox.Dispose();
}
}