String.TrimStart String.TrimStart String.TrimStart String.TrimStart Method

Definicja

Przeciążenia

TrimStart() TrimStart() TrimStart() TrimStart()
TrimStart(Char[]) TrimStart(Char[]) TrimStart(Char[]) TrimStart(Char[])

Usuwa wszystkie wiodące wystąpienia zestawu znaków określone w tablicy z bieżącego String obiektu.Removes all leading occurrences of a set of characters specified in an array from the current String object.

TrimStart(Char) TrimStart(Char) TrimStart(Char) TrimStart(Char)

TrimStart() TrimStart() TrimStart() TrimStart()

public:
 System::String ^ TrimStart();
public string TrimStart ();
member this.TrimStart : unit -> string
Public Function TrimStart () As String

Zwraca

TrimStart(Char[]) TrimStart(Char[]) TrimStart(Char[]) TrimStart(Char[])

Usuwa wszystkie wiodące wystąpienia zestawu znaków określone w tablicy z bieżącego String obiektu.Removes all leading occurrences of a set of characters specified in an array from the current String object.

public:
 System::String ^ TrimStart(... cli::array <char> ^ trimChars);
public string TrimStart (params char[] trimChars);
member this.TrimStart : char[] -> string
Public Function TrimStart (ParamArray trimChars As Char()) As String

Parametry

trimChars
Char[]

Tablica znaków Unicode do usunięcia lub null.An array of Unicode characters to remove, or null.

Zwraca

Ciąg, który pozostanie po wszystkich wystąpieniach znaków w trimChars parametrze, zostanie usunięty z początku bieżącego ciągu.The string that remains after all occurrences of characters in the trimChars parameter are removed from the start of the current string. Jeśli trimChars jest null lub jest pustą tablicą, zamiast tego są usuwane znaki odstępu.If trimChars is null or an empty array, white-space characters are removed instead.

Przykłady

W poniższym przykładzie przedstawiono podstawowe funkcje TrimStart metody:The following example demonstrates the basic functionality of the TrimStart method:

// TrimStart examples
string lineWithLeadingSpaces = "   Hello World!";
string lineWithLeadingSymbols = "$$$$Hello World!";
string lineWithLeadingUnderscores = "_____Hello World!";
string lineWithLeadingLetters = "xxxxHello World!";
string lineAfterTrimStart = string.Empty;

// Make it easy to print out and work with all of the examples
string[] lines = { lineWithLeadingSpaces, lineWithLeadingSymbols, lineWithLeadingUnderscores, lineWithLeadingLetters };

foreach (var line in lines)
{
    Console.WriteLine($"This line has leading characters: {line}");
}
// Output:
// This line has leading characters:    Hello World!
// This line has leading characters: $$$$Hello World!
// This line has leading characters: _____Hello World!
// This line has leading characters: xxxxHello World!

// A basic demonstration of TrimStart in action
lineAfterTrimStart = lineWithLeadingSpaces.TrimStart(' ');
Console.WriteLine($"This is the result after calling TrimStart: {lineAfterTrimStart}");
// This is the result after calling TrimStart: Hello World!   

// Since TrimStart accepts a character array of leading items to be removed as an argument,
// it's possible to do things like trim multiple pieces of data that each have different 
// leading characters,
foreach (var lineToEdit in lines)
{
    Console.WriteLine(lineToEdit.TrimStart(' ', '$', '_', 'x'));
}
// Result for each: Hello World!

// or handle pieces of data that have multiple kinds of leading characters 
var lineToBeTrimmed = "__###__ John Smith";
lineAfterTrimStart = lineToBeTrimmed.TrimStart('_', '#', ' ');
Console.WriteLine(lineAfterTrimStart);
// Result: John Smith
Public Sub Main()
   ' TrimStart Examples
   Dim lineWithLeadingSpaces as String = "   Hello World!"
Dim lineWithLeadingSymbols as String = "$$$$Hello World!"
   Dim lineWithLeadingUnderscores as String = "_____Hello World!"
   Dim lineWithLeadingLetters as String = "xxxxHello World!"
   Dim lineAfterTrimStart = String.Empty

   ' Make it easy to print out and work with all of the examples
   Dim lines As String() = { lineWithLeadingSpaces, line lineWithLeadingSymbols, lineWithLeadingUnderscores, lineWithLeadingLetters }

   For Each line As String in lines
     Console.WriteLine($"This line has leading characters: {line}")
   Next
   ' Output:
   ' This line has leading characters:    Hello World!
   ' This line has leading characters: $$$$Hello World!
   ' This line has leading characters: _____Hello World!
   ' This line has leading characters: xxxxHello World!

   Console.WriteLine($"This line has leading spaces: {lineWithLeadingSpaces}")
   ' This line has leading spaces:   Hello World!

   ' A basic demonstration of TrimStart in action
   lineAfterTrimStart = lineWithLeadingSpaces.TrimStart(" "c)
   Console.WriteLine($"This is the result after calling TrimStart: {lineAfterTrimStart}")
   ' This is the result after calling TrimStart: Hello World!

   ' Since TrimStart accepts a character array of leading items to be removed as an argument,
   ' it's possible to do things like trim multiple pieces of data that each have different 
   ' leading characters,
   For Each lineToEdit As String in lines
     Console.WriteLine(lineToEdit.TrimStart(" "c, "$"c, "_"c, "x"c ))
   Next
   ' Result for each: Hello World!

   ' or handle pieces of data that have multiple kinds of leading characters
   Dim lineToBeTrimmed as String = "__###__ John Smith"
   lineAfterTrimStart = lineToBeTrimmed.TrimStart("_"c , "#"c , " "c)
   Console.WriteLine(lineAfterTrimStart)
   ' Result: John Smith

 End Sub

W poniższym przykładzie zastosowano TrimStart metodę, aby przyciąć biały znak i znaki komentarza z wierszy kodu źródłowego.The following example uses the TrimStart method to trim white space and comment characters from lines of source code. Metoda zawija wywołanie do TrimStart i przekazuje go tablicę znaków, która zawiera spację i znak komentarza, który jest apostrofem (') w Visual Basic i ukośnik (/) w. C# StripCommentsThe 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#. Metoda TrimStart jest również wywoływana, aby usunąć wiodący biały znak podczas oceniania, czy ciąg jest komentarzem.The TrimStart method is also called to remove leading white space when evaluating whether a string is a comment.

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();
}
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   

Poniższy przykład ilustruje wywołanie StripComments metody.The following example then illustrates a call to the StripComments method.

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.
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.   

Uwagi

Metoda usuwa z bieżącego ciągu wszystkie znaki wiodące, które znajdują się trimChars w parametrze. TrimStartThe TrimStart method removes from the current string all leading characters that are in the trimChars parameter. Operacja Trim zostaje zatrzymana, gdy wystąpił znak, trimChars który nie znajduje się w.The trim operation stops when a character that is not in trimChars is encountered. Na przykład, jeśli bieżący ciąg ma wartość "123abc456xyz789" i trimChars zawiera cyfry od "1" do "9" TrimStart , metoda zwraca wartość "abc456xyz789".For example, if the current string is "123abc456xyz789" and trimChars contains the digits from "1" through "9", the TrimStart method returns "abc456xyz789".

Uwaga

TrimStart Jeśli metoda usuwa wszystkie znaki z bieżącego wystąpienia, ta metoda nie modyfikuje wartości bieżącego wystąpienia.If the TrimStart method removes any characters from the current instance, this method does not modify the value of the current instance. Zamiast tego zwraca nowy ciąg, w którym zostaną usunięte wszystkie wiodące białe znaki znajdujące się w bieżącym wystąpieniu.Instead, it returns a new string in which all leading white space characters found in the current instance are removed.

Uwagi dotyczące wywoływania

I starsze wersje obsługują wewnętrzną listę znaków białych, które ta metoda przycina, jeśli trimChars jest null lub pustą tablicą. .NET Framework 3.5 SP1.NET Framework 3.5 SP1The .NET Framework 3.5 SP1.NET Framework 3.5 SP1 and earlier versions maintains an internal list of white-space characters that this method trims if trimChars is null or an empty array. null IsWhiteSpace(Char) true Rozpoczynając od trimChars , jeśli jest lub pustą tablicę, metoda przycina wszystkie znaki białych znaków Unicode (oznacza to, że znaki, które generują wartość zwracaną, gdy są przesyłane do metody). Program .NET Framework 4.NET Framework 4Starting with the Program .NET Framework 4.NET Framework 4, if trimChars is null or an empty array, the method trims all Unicode white-space characters (that is, characters that produce a true return value when they are passed to the IsWhiteSpace(Char) method). Ze względu na tę zmianę Trim() Metoda .NET Framework 3.5 SP1.NET Framework 3.5 SP1 w programie i starszych wersjach usuwa dwa znaki, zerowe miejsce szerokości (u + 200B) i zerowej szerokości bez przerwy (u + Trim() FEFF), Program .NET Framework 4.NET Framework 4 która metoda w i nowszych wersjach. nie usuwaj.Because of this change, the Trim() method in the .NET Framework 3.5 SP1.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 Program .NET Framework 4.NET Framework 4 and later versions does not remove. Ponadto Trim() Metoda.NET Framework 3.5 SP1.NET Framework 3.5 SP1 w i starszych wersjach nie powoduje przycinania trzech białych znaków Unicode: SEPARATORy MONGOLSKIch samogłosek (U + 180E), WĄSKIe wolne miejsce (U + 202F) i średnie miejsce MATEMATYCZNe (U + 205F).In addition, the Trim() method in the .NET Framework 3.5 SP1.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).

Zobacz też

TrimStart(Char) TrimStart(Char) TrimStart(Char) TrimStart(Char)

public:
 System::String ^ TrimStart(char trimChar);
public string TrimStart (char trimChar);
member this.TrimStart : char -> string
Public Function TrimStart (trimChar As Char) As String

Parametry

trimChar
Char Char Char Char

Zwraca

Dotyczy