CODEWITHSUNDEEP
c#winforms
radiaku
radiaku

Reputation: 212

C# if else logic error

I doing some kind logic but its getting error?

here my code

private static void DrawText(String text, Font font, Color textColor, Color backColor)
{
    Image img = new Bitmap(640, 360);
    Graphics drawing = Graphics.FromImage(img);

    Color color = textColor;
    if (text.Length <= 80) {
        Rectangle displayRectangle =
            new Rectangle(new Point(20, 100), new Size(img.Width - 1, img.Height - 1));
    } else {
        Rectangle displayRectangle =
            new Rectangle(new Point(20, 80), new Size(img.Width - 1, img.Height - 1));
    }
    StringFormat format1 = new StringFormat(StringFormatFlags.NoClip);
    StringFormat format2 = new StringFormat(format1);

     // ERROR ON NEXT LINE
    drawing.DrawString(text, font, Brushes.Red, (RectangleF)displayRectangle, format2);

    drawing.Dispose();
    string fileName = "f.png";
    string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, fileName);
    img.Save(path, System.Drawing.Imaging.ImageFormat.Png);

    img.Dispose();
}

the error is

Error 1 The name 'displayRectangle' does not exist in the current context C:\Documents and Settings\admin\My Documents\Visual Studio 2008>\Projects\template\template\Form1.cs 119 69 template

At this line

drawing.DrawString(text, font, Brushes.Red, (RectangleF)displayRectangle, format2);

In php the logic was right, but when in C# its getting error?, How doing this logic in C#?

Any help? ( Still learning C# by doing :D )

Upvotes: 1

Views: 693

Answers (7)

DmitryK
DmitryK

Reputation: 1333

I think it is because of your initialization.

The way it should be:

 private static void DrawText(String text, Font font, Color textColor, Color backColor)
 {
    Rectangle displayRectangle; // YOU MUST DECLARE IT HERE OR OUTSIDE THE FUNCTION,
                                // but never inside an "if" statement.
    Image img = new Bitmap(640, 360);
    Graphics drawing = Graphics.FromImage(img);

    Color color = textColor;
    if (text.Length <= 80) {
        displayRectangle =
           new Rectangle(new Point(20, 100), new Size(img.Width - 1, img.Height - 1));
    } else {
        displayRectangle =
           new Rectangle(new Point(20, 80), new Size(img.Width - 1, img.Height - 1));
    }
    StringFormat format1 = new StringFormat(StringFormatFlags.NoClip);
    StringFormat format2 = new StringFormat(format1);

    // ERROR ON NEXT LINE
    drawing.DrawString(text, font, Brushes.Red, (RectangleF)displayRectangle, format2);

    drawing.Dispose();
    string fileName = "f.png";
    string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, fileName);
    img.Save(path, System.Drawing.Imaging.ImageFormat.Png);

    img.Dispose();
}

Upvotes: 1

Steve Niles
Steve Niles

Reputation: 822

If you really want to be concise, you can replace the entire IF/ELSE block with the following line of code:

var displayRectangle = new Rectangle(20, (text.Length > 80 ? 80 : 100), img.Width - 1, img.Height - 1);

Upvotes: 1

COLD TOLD
COLD TOLD

Reputation: 13579

Move the Rectangle definition above the if else block, so that it doesn't go out of scope.

Rectangle displayRectangle;

if (text.Length <= 80)
{
    displayRectangle = new Rectangle(new Point(20, 100), new Size(img.Width  img.Height - 1));
}
else
{
    displayRectangle = new Rectangle(new Point(20, 80), new Size(img.Width -  img.Height - 1));
}

Upvotes: 12

Tim Schmelter
Tim Schmelter

Reputation: 460048

You cannot use a variable which is declared outside of the current scope. You have declared displayRectangle inside of the if-clause, hence it is "invisible" outside of it.

Instead declare it outside and initialize it inside:

Rectangle displayRectangle = Rectangle.Empty;
if (text.Length <= 80)
{
     displayRectangle = new Rectangle(new Point(20, 100), new Size(img.Width - 1, img.Height - 1));
}
else
{
    displayRectangle = new Rectangle(new Point(20, 80), new Size(img.Width - 1, img.Height - 1));
}

8.5.1 Local variable declarations

The scope of a local variable declared in a local-variable-declaration is the block in which the declaration occurs. It is an error to refer to a local variable in a textual position that precedes the local-variable-declarator of the local variable. Within the scope of a local variable, it is a compile-time error to declare another local variable or constant with the same name.

Upvotes: 3

SWeko
SWeko

Reputation: 30882

Basically, it doesn't work that way :)

Variables defined within an if or an else block, between the { and the } are only visible in that block. That is why you were able to define it twice, once in the if branch and once in the else branch.

So the solution is to declare the variable before the branching, and just set it in the if/else branches.

Rectangle displayRectangle; //declaration

if (text.Length <= 80)
{
  //setting
  displayRectangle = new Rectangle(new Point(20, 100), new Size(img.Width - 1, img.Height - 1));
}
else
{
  //setting
  displayRectangle = new Rectangle(new Point(20, 80), new Size(img.Width - 1, img.Height - 1));
}
....
//usage
drawing.DrawString(text, font, Brushes.Red, (RectangleF)displayRectangle, format2);

In addition, the C# compiler is smart enough to detect that the variable is set in each branch, so that it will definitely be set when it reaches it's usage code. However, if it's not set in every branch, that would be a compile error, e.g.

if (text.Length <= 80)
{
  displayRectangle = ...;
}
else if (text.Length > 40)
{

  displayRectangle = ...;
}

Upvotes: 5

Darin Dimitrov
Darin Dimitrov

Reputation: 1038710

You could define the displayRectangle variable outside of your if/else logic:

Rectangle displayRectangle;
if (text.Length <= 80)
{
    displayRectangle = new Rectangle(new Point(20, 100), new Size(img.Width - 1, img.Height - 1));
}
else
{
    displayRectangle = new Rectangle(new Point(20, 80), new Size(img.Width - 1, img.Height - 1));
}

Now this variable will be known to the outer scope.

Upvotes: 4

Steve
Steve

Reputation: 6424

Move your variable declaration outside the block:

    Rectangle displayRectangle;
    if (text.Length <= 80)
    {
        displayRectangle = new Rectangle(new Point(20, 100), new Size(img.Width - 1, img.Height - 1));
    }
    else
    {
        displayRectangle = new Rectangle(new Point(20, 80), new Size(img.Width - 1, img.Height - 1));
    }

The problem is the scope of displayRectangle in your code. As soon as the block is finished executing, displayRectangle is completely forgotten about since it's declared inside the block.

Upvotes: 1

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