Trim and remove characters from strings in .NET

If you're parsing a sentence into individual words, you might end up with words that have blank spaces (also called white spaces) on either end of the word. In this situation, you can use one of the trim methods in the System.String class to remove any number of spaces or other characters from a specified position in the string. The following table describes the available trim methods:

Trim

You can easily remove white spaces from both ends of a string by using the String.Trim method, as shown in the following example:

String^ MyString = " Big   ";
Console::WriteLine("Hello{0}World!", MyString);
String^ TrimString = MyString->Trim();
Console::WriteLine("Hello{0}World!", TrimString);
// The example displays the following output:
//       Hello Big   World!
//       HelloBigWorld!        

string MyString = " Big   ";
Console.WriteLine("Hello{0}World!", MyString);
string TrimString = MyString.Trim();
Console.WriteLine("Hello{0}World!", TrimString);
//       The example displays the following output:
//             Hello Big   World!
//             HelloBigWorld!

Dim MyString As String = " Big   "
Console.WriteLine("Hello{0}World!", MyString)
Dim TrimString As String = MyString.Trim()
Console.WriteLine("Hello{0}World!", TrimString)
' The example displays the following output:
'       Hello Big   World!
'       HelloBigWorld!        

You can also remove characters that you specify in a character array from the beginning and end of a string. The following example removes white-space characters, periods, and asterisks:

using System;

public class Example
{
   public static void Main()
   {
      String header = "* A Short String. *";
      Console.WriteLine(header);
      Console.WriteLine(header.Trim( new Char[] { ' ', '*', '.' } ));
   }
}
// The example displays the following output:
//       * A Short String. *
//       A Short String

Module Example
    Public Sub Main()
        Dim header As String = "* A Short String. *"
        Console.WriteLine(header)
        Console.WriteLine(header.Trim({" "c, "*"c, "."c}))
    End Sub
End Module
' The example displays the following output:
'       * A Short String. *
'       A Short String

TrimEnd

The String.TrimEnd method removes characters from the end of a string, creating a new string object. An array of characters is passed to this method to specify the characters to be removed. The order of the elements in the character array doesn't affect the trim operation. The trim stops when a character not specified in the array is found.

The following example removes the last letters of a string using the TrimEnd method. In this example, the position of the 'r' character and the 'W' character are reversed to illustrate that the order of characters in the array doesn't matter. Notice that this code removes the last word of MyString plus part of the first.

String^ MyString = "Hello World!";
array<Char>^ MyChar = {'r','o','W','l','d','!',' '};
String^ NewString = MyString->TrimEnd(MyChar);
Console::WriteLine(NewString);

string MyString = "Hello World!";
char[] MyChar = {'r','o','W','l','d','!',' '};
string NewString = MyString.TrimEnd(MyChar);
Console.WriteLine(NewString);

Dim MyString As String = "Hello World!"
Dim MyChar() As Char = {"r", "o", "W", "l", "d", "!", " "}
Dim NewString As String = MyString.TrimEnd(MyChar)
Console.WriteLine(NewString)

This code displays He to the console.

The following example removes the last word of a string using the TrimEnd method. In this code, a comma follows the word Hello and because the comma isn't specified in the array of characters to trim, the trim ends at the comma.

String^ MyString = "Hello, World!";
array<Char>^ MyChar = {'r','o','W','l','d','!',' '};
String^ NewString = MyString->TrimEnd(MyChar);
Console::WriteLine(NewString);

string MyString = "Hello, World!";
char[] MyChar = {'r','o','W','l','d','!',' '};
string NewString = MyString.TrimEnd(MyChar);
Console.WriteLine(NewString);

Dim MyString As String = "Hello, World!"
Dim MyChar() As Char = {"r", "o", "W", "l", "d", "!", " "}
Dim NewString As String = MyString.TrimEnd(MyChar)
Console.WriteLine(NewString)

This code displays Hello, to the console.

TrimStart

The String.TrimStart method is similar to the String.TrimEnd method except that it creates a new string by removing characters from the beginning of an existing string object. An array of characters is passed to the TrimStart method to specify the characters to be removed. As with the TrimEnd method, the order of the elements in the character array doesn't affect the trim operation. The trim stops when a character not specified in the array is found.

The following example removes the first word of a string. In this example, the position of the 'l' character and the 'H' character are reversed to illustrate that the order of characters in the array doesn't matter.

String^ MyString = "Hello World!";
array<Char>^ MyChar = {'e', 'H','l','o',' ' };
String^ NewString = MyString->TrimStart(MyChar);
Console::WriteLine(NewString);

string MyString = "Hello World!";
char[] MyChar = {'e', 'H','l','o',' ' };
string NewString = MyString.TrimStart(MyChar);
Console.WriteLine(NewString);

Dim MyString As String = "Hello World!"
Dim MyChar() As Char = {"e", "H", "l", "o", " "}
Dim NewString As String = MyString.TrimStart(MyChar)
Console.WriteLine(NewString)

This code displays World! to the console.

Remove

The String.Remove method removes a specified number of characters that begin at a specified position in an existing string. This method assumes a zero-based index.

The following example removes 10 characters from a string beginning at position five of a zero-based index of the string.

String^ MyString = "Hello Beautiful World!";
Console::WriteLine(MyString->Remove(5,10));
// The example displays the following output:
//         Hello World!        

string MyString = "Hello Beautiful World!";
Console.WriteLine(MyString.Remove(5,10));
// The example displays the following output:
//         Hello World!

Dim MyString As String = "Hello Beautiful World!"
Console.WriteLine(MyString.Remove(5, 10))
' The example displays the following output:
'         Hello World!        

Replace

You can also remove a specified character or substring from a string by calling the String.Replace(String, String) method and specifying an empty string (String.Empty) as the replacement. The following example removes all commas from a string:

using System;

public class Example
{
   public static void Main()
   {
      String phrase = "a cold, dark night";
      Console.WriteLine("Before: {0}", phrase);
      phrase = phrase.Replace(",", "");
      Console.WriteLine("After: {0}", phrase);
   }
}
// The example displays the following output:
//       Before: a cold, dark night
//       After: a cold dark night

Module Example
    Public Sub Main()
        Dim phrase As String = "a cold, dark night"
        Console.WriteLine("Before: {0}", phrase)
        phrase = phrase.Replace(",", "")
        Console.WriteLine("After: {0}", phrase)
    End Sub
End Module
' The example displays the following output:
'       Before: a cold, dark night
'       After: a cold dark night

See also

• Basic String Operations