Char.IsControl Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

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

Overloads

IsControl(Char)	Indicates whether the specified Unicode character is categorized as a control character.
IsControl(String, Int32)	Indicates whether the character at the specified position in a specified string is categorized as a control character.

Remarks

Control characters are formatting and other non-printing characters, such as ACK, BEL, CR, FF, LF, and VT. The Unicode standard assigns code points from \U0000 to \U001F, \U007F, and from \U0080 to \U009F to control characters. 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.

IsControl(Char)

Source:

Char.cs

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

public:
 static bool IsControl(char c);

public static bool IsControl (char c);

static member IsControl : char -> bool

Public Shared Function IsControl (c As Char) As Boolean

Parameters

c

Char

The Unicode character to evaluate.

Returns

Boolean

true if c is a control character; otherwise, false.

Examples

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

using namespace System;

void main()
{
   int charsWritten = 0;
      
   for (int ctr = 0x00; ctr <= 0xFFFF; ctr++)
   {
      wchar_t ch = ctr;
      if (Char::IsControl(ch))
      {
         Console::Write(L"\U{0:X4}    ", ctr);
         charsWritten++;
         if (charsWritten % 6 == 0)
            Console::WriteLine();
      }     
   }  
}
// 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 ControlChars
{
   public static void Main()
   {
      int charsWritten = 0;

      for (int ctr = 0x00; ctr <= 0xFFFF; ctr++)
      {
         char ch = Convert.ToChar(ctr);
         if (char.IsControl(ch))
         {
            Console.Write(@"\U{0:X4}    ", ctr);
            charsWritten++;
            if (charsWritten % 6 == 0)
               Console.WriteLine();
         }
      }
   }
}
// The example displays the following output to the console:
//       \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

open System

let mutable charsWritten = 0

for i in 0x00..0xFFFF do
    let ch = Convert.ToChar i
    if Char.IsControl ch then
        printf $"\\U{i:X4}    "
        charsWritten <- charsWritten + 1
        if charsWritten % 6 = 0 then
            printfn ""

// The example displays the following output to the console:
//       \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

Module ControlChars
   Public Sub Main()
      Dim charsWritten As Integer = 0

      For ctr As Integer = &H0 To &HFFFF
         Dim ch As Char = Convert.ToChar(ctr)
         
         If Char.IsControl(ch) Then
            Console.Write("\U{0:X4}    ", ctr)
            charsWritten += 1 
            If (charsWritten Mod 6) = 0 Then 
               Console.WriteLine()
            End If    
         End If
      Next
   End Sub
End Module
' The example displays the following output to the console:
'       \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

IsControl(String, Int32)

Source:

Char.cs

Indicates whether the character at the specified position in a specified string is categorized as a control character.

public:
 static bool IsControl(System::String ^ s, int index);

public static bool IsControl (string s, int index);

static member IsControl : string * int -> bool

Public Shared Function IsControl (s As String, index As Integer) As Boolean

Parameters

s

String

A string.

index

Int32

The position of the character to evaluate in s.

Returns

Boolean

true if the character at position index in s is a control character; otherwise, false.

Exceptions

ArgumentNullException

s is null.

ArgumentOutOfRangeException

index is less than zero or greater than the last position in s.

Examples

The following example enumerates the characters in a string and determines whether any are control characters.

using namespace System;

void main()
{
      String ^ sentence = "This is a " + Environment::NewLine + "two-line sentence.";
      for (int ctr = 0; ctr < sentence->Length; ctr++)
      {
         if (Char::IsControl(sentence, ctr))
           Console::WriteLine("Control character \\U{0} found in position {1}.", 
                              Convert::ToInt32(sentence[ctr]).ToString("X4"), ctr);
      }
}
// The example displays the following output:
//       Control character \U000D found in position 10.
//       Control character \U000A found in position 11.

using System;

public class ControlChar
{
   public static void Main()
   {
      string sentence = "This is a " + Environment.NewLine + "two-line sentence.";
      for (int ctr = 0; ctr < sentence.Length; ctr++)
      {
         if (Char.IsControl(sentence, ctr))
           Console.WriteLine("Control character \\U{0} found in position {1}.",
             Convert.ToInt32(sentence[ctr]).ToString("X4"), ctr);
      }
   }
}
// The example displays the following output to the console:
//       Control character \U000D found in position 10.
//       Control character \U000A found in position 11.

open System

let sentence = "This is a " + Environment.NewLine + "two-line sentence."

for i = 0 to sentence.Length - 1 do
    if Char.IsControl(sentence, i) then
        printfn $"Control character \\U{Convert.ToInt32 sentence[i]:X4} found in position {i}."

// The example displays the following output to the console:
//       Control character \U000D found in position 10.
//       Control character \U000A found in position 11.

Module ControlChar
   Public Sub Main()
      Dim sentence As String = "This is a " & vbCrLf & "two-line sentence."
      For ctr As Integer = 0 to sentence.Length - 1
         If Char.IsControl(sentence, ctr) Then
            Console.WriteLine("Control character \U{0} found in position {1}.", _
             Convert.ToInt32(sentence.Chars(ctr)).ToString("X4"), ctr)
          End If
       Next   
   End Sub
End Module
' The example displays the following output to the console:
'       Control character \U000D found in position 10.
'       Control character \U000A found in position 11.