Question

    private void pictureBox1_Paint_1(object sender, PaintEventArgs e)
    {
        Pen graphPen = new Pen(Color.Red, 2);
        Point pt1D = new Point();
        Point pt2D = new Point();
        pt1D.X = textBox3.Text.ToString();
        e.Graphics.DrawLine(graphPen, pt1D, pt2D);

    }

我在第6行收到错误：cannot convert type string to int.

Answer 1

其他人都是正确的，您需要转换价值，但仅使用int.Parse可能会导致错误，val = int.TryParse不是您使用int.TryParse的方式，因此，更正：

int result = 0;
if (int.TryParse(textBox3.Text, out result)) {
  pt1D.X = result;
} else {
  // input isn't an integer
}

另外要提到的是Pen实现IDisposable，所以你应该在使用完之后处理它;您可以通过明确调用Dispose或using：

来执行此操作

using (Pen graphPen = new Pen(Color.Red, 2)) {
  // do what you need with the pen, 
  // it will be disposed when exiting this scope
}

Answer 2

您需要将文本框中的字符串转换为整数：

private void pictureBox1_Paint_1(object sender, PaintEventArgs e)
{
    Pen graphPen = new Pen(Color.Red, 2);
    Point pt1D = new Point();
    Point pt2D = new Point();
    int xCoord = int.Parse(textBox3.Text);
    pt1D.X = xCoord;
    e.Graphics.DrawLine(graphPen, pt1D, pt2D);

}

Answer 3

更改为：

private void pictureBox1_Paint_1(object sender, PaintEventArgs e)
{
    int value = 0;
    Pen graphPen = new Pen(Color.Red, 2);
    Point pt1D = new Point();
    Point pt2D = new Point();
    pt1D.X = (int.tryParse(textBox3.Text, out value)) ? value : 0;
    e.Graphics.DrawLine(graphPen, pt1D, pt2D);

}

在以下代码的第6行获取错误

3 个答案: