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String.Trim Method ()

 

Removes all leading and trailing white-space characters from the current String object.

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

Public Function Trim As String

Return Value

Type: System.String

The string that remains after all white-space characters are removed from the start and end of the current string. If no characters can be trimmed from the current instance, the method returns the current instance unchanged.

The Trim method removes from the current string all leading and trailing white-space characters. Each leading and trailing trim operation stops when a non-white-space character is encountered. For example, if the current string is "   abc   xyz   ", the Trim method returns "abc   xyz". To remove white-space characters between words in a string, use a .NET Framework Regular Expressions.

System_CAPS_note Note

If the Trim method removes any characters from the current instance, this method does not modify the value of the current instance. Instead, it returns a new string in which all leading and trailing white space characters found in the current instance are removed.

If the current string equals Empty or all the characters in the current instance consist of white-space characters, the method returns Empty.

White-space characters are defined by the Unicode standard. The Trim() method removes any leading and trailing characters that produce a return value of true when they are passed to the Char.IsWhiteSpace method.

Notes to Callers:

The .NET Framework 3.5 SP1 and earlier versions maintain an internal list of white-space characters that this method trims. Starting with the .NET Framework 4, the method trims all Unicode white-space characters (that is, characters that produce a true return value when they are passed to the Char.IsWhiteSpace method). Because of this change, the Trim method in the .NET Framework 3.5 SP1 and earlier versions removes two characters, ZERO WIDTH SPACE (U+200B) and ZERO WIDTH NO-BREAK SPACE (U+FEFF), that the Trim method in the .NET Framework 4and later versions does not remove. In addition, the Trim method in the .NET Framework 3.5 SP1 and earlier versions does not trim three Unicode white-space characters: MONGOLIAN VOWEL SEPARATOR (U+180E), NARROW NO-BREAK SPACE (U+202F), and MEDIUM MATHEMATICAL SPACE (U+205F).

The following example uses the String.Trim() method to remove any extra white space from strings entered by the user before concatenating them.

Module Example
   Public Sub Main()
      Console.Write("Enter your first name: ")
      Dim firstName As String = Console.ReadLine()

      Console.Write("Enter your middle name or initial: ")
      Dim middleName As String = Console.ReadLine()

      Console.Write("Enter your last name: ")
      Dim lastName As String = Console.ReadLine

      Console.WriteLine()
      Console.WriteLine("You entered '{0}', '{1}', and '{2}'.", _
                        firstName, middleName, lastName)

      Dim name As String = ((firstName.Trim() + " " + middleName.Trim()).Trim() _
                           + " " + lastName.Trim()).Trim()                        
      Console.WriteLine("The result is " + name + ".")
   End Sub
End Module
' The following is possible output from this example:
'       Enter your first name:    John
'       Enter your middle name or initial:
'       Enter your last name:    Doe
'       
'       You entered '   John  ', '', and '   Doe'.
'       The result is John Doe.
Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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