如何在C＃编程中执行循环？

Question

I have to allow 20 balls to move around the screen. I would like to know how do I use a loop so I would not have to type the codes out long. Currently, the codes I have are

for (int i = 0; i < ballSpeedXAxis.Length; i++)
        {
            ballSpeedXAxis[i] = 1;
        }

for (int i = 0; i < ballSpeedYAxis.Length; i++)
        {
            ballSpeedYAxis[i] = 1;
        } 

private void OnUpdate(object sender, object e)
{
Canvas.SetLeft(this.ball1, this.ballSpeedXAxis[1] + Canvas.GetLeft(this.ball1));
Canvas.SetTop(this.ball1, this.ballSpeedYAxis[1] + Canvas.GetTop(this.ball1));
Canvas.SetLeft(this.ball2, this.ballSpeedXAxis[2] + Canvas.GetLeft(this.ball2));
Canvas.SetTop(this.ball2, this.ballSpeedXAxis[2] + Canvas.GetTop(this.ball2));
...
Canvas.SetLeft(this.ball20, this.ballSpeedXAxis[20] + Canvas.GetLeft(this.ball20));
Canvas.SetTop(this.ball20, this.ballSpeedXAxis[20] + Canvas.GetTop(this.ball20));
}

ball1, ball2 ... ball3 are images name.

Answer 1

There are varying ways.. the most obvious being instead of this:

Image ball1;
Image ball2;
Image ball3;
// .. etc ...

You would put those in an array also:

Image[] balls = new Image[20];

..same with your speeds. Then you can change your update method to this:

private void OnUpdate(object sender, object e) {
    for (int i = 0; i < balls.Length; i++) {
        Canvas.SetLeft(balls[i], ballSpeedXAxis[i] + Canvas.GetLeft(balls[i]));
        Canvas.SetTop(balls[i], ballSpeedYAxis[i] + Canvas.GetTop(balls[i]));
    }
}

Others include putting the already created images into a List<Image> .. but that's a bit yuck.