Removes all leading occurrences of a set of characters specified in an array from the current String object.
Assembly: mscorlib (in mscorlib.dll)
Public Function TrimStart ( _
ParamArray trimChars As Char() _
) As Stringpublic string TrimStart(
params char[] trimChars
)public:
String^ TrimStart(
... array<wchar_t>^ trimChars
)member TrimStart :
trimChars:char[] -> string
Parameters
- trimChars
- Type:
array< System. . :: . Char> [] () []
An array of Unicode characters to remove, ornull Nothing nullptr a null reference (Nothing in Visual Basic) .
Return Value
Type: SystemThe string that remains after all occurrences of characters in the trimChars parameter are removed from the start of the current string. If trimChars is
The TrimStart method removes from the current string all leading characters that are in the trimChars parameter. The trim operation stops when a character that is not in trimChars is encountered. For example, if the current string is "123abc456xyz789" and trimChars contains the digits from "1" through "9", the TrimStart method returns "abc456xyz789".
.gif) Note |
|---|
This method does not modify the value of the current instance. Instead, it returns a new string in which all leading white space characters found in the current instance are removed. |
The .NET Framework 3.5 SP1 and earlier versions maintains an internal list of white-space characters that this method trims if trimChars is
The following example uses the TrimStart method to trim white space and comment characters from lines of source code. The StripComments method wraps a call to TrimStart and passes it a character array that contains a space and the comment character, which is an apostrophe ( ' ) in Visual Basic and a slash ( / ) in C#. The TrimStart method is also called to remove leading white space when evaluating whether a string is a comment.
Public Shared Function StripComments(lines() As String) As String()
Dim lineList As New List(Of String)
For Each line As String In lines
If line.TrimStart(" "c).StartsWith("'") Then
linelist.Add(line.TrimStart("'"c, " "c))
End If
Next
Return lineList.ToArray()
End Function
public static string[] StripComments(string[] lines)
{
List<string> lineList = new List<string>();
foreach (string line in lines)
{
if (line.TrimStart(' ').StartsWith("//"))
lineList.Add(line.TrimStart(' ', '/'));
}
return lineList.ToArray();
}
The following example then illustrates a call to the StripComments method.
Public Shared Sub Main()
Dim lines() As String = {"Public Module HelloWorld", _
" Public Sub Main()", _
" ' This code displays a simple greeting", _
" ' to the console.", _
" Console.WriteLine(""Hello, World."")", _
" End Sub", _
" End Module"}
Console.WriteLine("Code before call to StripComments:")
For Each line As String In lines
Console.WriteLine(" {0}", line)
Next
Dim strippedLines() As String = StripComments(lines)
Console.WriteLine("Code after call to StripComments:")
For Each line As String In strippedLines
Console.WriteLine(" {0}", line)
Next
End Sub
' This code produces the following output to the console:
' Code before call to StripComments:
' Public Module HelloWorld
' Public Sub Main()
' ' This code displays a simple greeting
' ' to the console.
' Console.WriteLine("Hello, World.")
' End Sub
' End Module
' Code after call to StripComments:
' This code displays a simple greeting
' to the console.
public static void Main()
{
string[] lines= {"using System;",
"",
"public class HelloWorld",
"{",
" public static void Main()",
" {",
" // This code displays a simple greeting",
" // to the console.",
" Console.WriteLine(\"Hello, World.\");",
" }",
"}"};
Console.WriteLine("Before call to StripComments:");
foreach (string line in lines)
Console.WriteLine(" {0}", line);
string[] strippedLines = StripComments(lines);
Console.WriteLine("After call to StripComments:");
foreach (string line in strippedLines)
Console.WriteLine(" {0}", line);
}
// This code produces the following output to the console:
// Before call to StripComments:
// using System;
//
// public class HelloWorld
// {
// public static void Main()
// {
// // This code displays a simple greeting
// // to the console.
// Console.WriteLine("Hello, World.");
// }
// }
// After call to StripComments:
// This code displays a simple greeting
// to the console.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.