• Article

Char.IsControl Method (Char)

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Indicates whether the specified Unicode character is categorized as a control character.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public Shared Function IsControl ( _
    c As Char _
) As Boolean

public static bool IsControl(
    char c
)

Parameters

Return Value

Type: System.Boolean
true if c is a control character; otherwise, false.

Remarks

Control characters are non-printing and formatting characters, such as ACK, BEL, CR, FF, LF, and VT. The Unicode standard assigns the following code points to control characters: from \U0000 to \U001F, \U007F, and from \U0080 to \U009F. According to the Unicode standard, these values are to be interpreted as control characters unless their use is otherwise defined by an application. Valid control characters are members of the UnicodeCategory.Control category.

Examples

The following example lists the Unicode code point of each of the control characters.

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim charsWritten As Integer = 0

      For ctr As Integer = &H0 To &HFFFF
         Dim ch As Char = Convert.ToChar(ctr)

         If Char.IsControl(ch) Then
            outputBlock.Text += String.Format("\U{0:X4}    ", ctr)
            charsWritten += 1
            If (charsWritten Mod 6) = 0 Then
               outputBlock.Text &= vbCrLf
            End If
         End If
      Next
   End Sub
End Module
' The example displays the following output:
'       \U0000    \U0001    \U0002    \U0003    \U0004    \U0005
'       \U0006    \U0007    \U0008    \U0009    \U000A    \U000B
'       \U000C    \U000D    \U000E    \U000F    \U0010    \U0011
'       \U0012    \U0013    \U0014    \U0015    \U0016    \U0017
'       \U0018    \U0019    \U001A    \U001B    \U001C    \U001D
'       \U001E    \U001F    \U007F    \U0080    \U0081    \U0082
'       \U0083    \U0084    \U0085    \U0086    \U0087    \U0088
'       \U0089    \U008A    \U008B    \U008C    \U008D    \U008E
'       \U008F    \U0090    \U0091    \U0092    \U0093    \U0094
'       \U0095    \U0096    \U0097    \U0098    \U0099    \U009A
'       \U009B    \U009C    \U009D    \U009E    \U009F

using System;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      int charsWritten = 0;

      for (int ctr = 0x00; ctr <= 0xFFFF; ctr++)
      {
         char ch = Convert.ToChar(ctr);
         if (char.IsControl(ch))
         {
            outputBlock.Text += String.Format(@"\U{0:X4}    ", ctr);
            charsWritten++;
            if (charsWritten % 6 == 0)
               outputBlock.Text += "\n";
         }
      }
   }
}
// The example displays the following output:
//       \U0000    \U0001    \U0002    \U0003    \U0004    \U0005
//       \U0006    \U0007    \U0008    \U0009    \U000A    \U000B
//       \U000C    \U000D    \U000E    \U000F    \U0010    \U0011
//       \U0012    \U0013    \U0014    \U0015    \U0016    \U0017
//       \U0018    \U0019    \U001A    \U001B    \U001C    \U001D
//       \U001E    \U001F    \U007F    \U0080    \U0081    \U0082
//       \U0083    \U0084    \U0085    \U0086    \U0087    \U0088
//       \U0089    \U008A    \U008B    \U008C    \U008D    \U008E
//       \U008F    \U0090    \U0091    \U0092    \U0093    \U0094
//       \U0095    \U0096    \U0097    \U0098    \U0099    \U009A
//       \U009B    \U009C    \U009D    \U009E    \U009F

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.