Double Var keeps adding to increment

-Synopsis-
I've recently developed a simple physics program, which presents a modifiable velocity setting.

It updates the current time(in secs) as well as the current position which happens to add to the

current position the missile image is set to.

-Problem-
Overall the program works just fine, there just happens to be one problem , in order to update the

newtime I've created a double variable called "Currentime" which is set equal to the current text in

the textbox plus the time increment(0.5). This is called by a timer object which is created for the

form and calls it every 0.05 seconds. The thing is though that everytime i reset the time fields to

zero it for some reason adds like this 0.5 ,1.0, 1.5, 2.0 etc (1st round) then 1.0 ,2.0, 3.0., 4.0,etc(2nd round) and keeps increasing

if you need more code or want a copy i can provide it i really need help i don't know how to solve it
to see exactly what i mean here is segment of the code
private void button1_Click(object sender, EventArgs e)// If this button is clicked start the timer
{
timestarted = true;
this.timer1.Enabled = true;
this.timer1.Interval = 100;
this.timer1.Start();
this.timer1.Tick += new EventHandler(timer1_Tick);
}

void timer1_Tick(object sender, EventArgs e)
{
this.textBox1.ResumeLayout();
Update();
}
public void Update()
{

double newtime = double.Parse(this.textBox1.Text) + double.Parse(this.textBox4.Text);
this.pictureBox1.Refresh();
//textbox 1 = time text textbox 4 = time increment( 0.5)

System.Drawing.Image Missile = Image.FromFile(@"C:\Users\Brandon Fleury\Documents\Visual Studio 2008\2dProjectileTest\2dProjectileTest\Resources\Missile.jpg");
InitialMissileHeight = 332.0;
InitialTime = 0.0;
InitialVelocity = 20.0;
InitialAcceleration = 0.0;
// Y-Position -- Position(Final) = Posiiton(Initial) + Velocity(Initial)* Current Time + 1/2*Acceleration* Current Time*Current Time

double Yposition = InitialMissileHeight - double.Parse(this.textBox1.Text) * Double.Parse(this.textBox1.Text); ;
double newheight = InitialMissileHeight - Yposition;
if (newheight <500.0)
{
this.textBox1.Text = newtime.ToString();
this.textBox3.Text = newheight.ToString();
this.textBox3.Update();
this.pictureBox1.CreateGraphics().DrawImage(Missile, 225, Convert.ToInt32(Yposition), 10, 10);
this.pictureBox1.Update();

}

}

Just for sure, what is expected behavior?
1st: 0.0 0.5 1.0 1.5 2.0 ...
2nd: 0.0 0.5 1.0 1.5 2.0 ...
3rd: 0.0 0.5 1.0 1.5 2.0 ...

Why do you add another event handler with every button click?

Quote:

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Originally Posted by zips

Why do you add another event handler with every button click?

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Code:

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this.timer1.Tick += new EventHandler(timer1_Tick);

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I would check this first. Either remove the event handler later in the code like so...

Code:

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this.timer1.Tick -= new EventHandler(timer1_Tick);

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Or add the event handler outside of the button click but before the button click takes place, like a constructor or another method thats called on the constructor. This way its only added once.

ah presto that was it thanks guys i appreciate it it works just fine now, i have to take note of that for future projects thanks tons and it wasn't intentional btw just a small thing i overlooked