String.TrimStart Método

public:
 System::String ^ TrimStart();

public string TrimStart ();

member this.TrimStart : unit -> string

Public Function TrimStart () As String

Devoluciones

String

La cadena que queda después de quitar todos los caracteres de espacio en blanco del principio de la cadena actual.The string that remains after all white-space characters are removed from the start of the current string. Si no se puede quitar ningún carácter de la instancia actual, el método devuelve la instancia actual sin cambios.If no characters can be trimmed from the current instance, the method returns the current instance unchanged.

Comentarios

El TrimStart método quita de la cadena actual todos los caracteres de espacio en blanco iniciales.The TrimStart method removes from the current string all leading white-space characters. La operación de recorte se detiene cuando se encuentra un carácter que no sea un espacio en blanco.The trim operation stops when a non white-space character is encountered. Por ejemplo, si la cadena actual es "ABC XYZ", el TrimStart método devuelve "ABC XYZ".For example, if the current string is " abc xyz ", the TrimStart method returns "abc xyz ".

public:
 System::String ^ TrimStart(... cli::array <char> ^ trimChars);

public string TrimStart (params char[] trimChars);

public string TrimStart (params char[]? trimChars);

member this.TrimStart : char[] -> string

Public Function TrimStart (ParamArray trimChars As Char()) As String

Parámetros

Devoluciones

String

Cadena que queda una vez quitadas todas las apariciones de los caracteres especificados por el parámetro trimChars del principio de la cadena actual.The string that remains after all occurrences of characters in the trimChars parameter are removed from the start of the current string. Si trimChars es null o una matriz vacía, se quitarán los caracteres de espacio en blanco.If trimChars is null or an empty array, white-space characters are removed instead. Si no se puede quitar ningún carácter de la instancia actual, el método devuelve la instancia actual sin cambios.If no characters can be trimmed from the current instance, the method returns the current instance unchanged.

Ejemplos

En el ejemplo siguiente se muestra la funcionalidad básica del TrimStart método: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

En el ejemplo siguiente se utiliza el TrimStart método para recortar el espacio en blanco y los caracteres de comentario de las líneas de código fuente.The following example uses the TrimStart method to trim white space and comment characters from lines of source code. El StripComments método ajusta una llamada a TrimStart y le pasa una matriz de caracteres que contiene un espacio y el carácter de comentario, que es un apóstrofo (') en Visual Basic y una barra diagonal (/) en C#.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#. TrimStartTambién se llama al método para quitar el espacio en blanco inicial al evaluar si una cadena es un comentario.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   

En el ejemplo siguiente se muestra la llamada al método StripComments.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.   

Comentarios

El TrimStart(System.Char[]) método quita de la cadena actual todos los caracteres iniciales que se encuentran en el trimChars parámetro.The TrimStart(System.Char[]) method removes from the current string all leading characters that are in the trimChars parameter. La operación de recorte se detiene cuando se encuentra un carácter que no está en trimChars .The trim operation stops when a character that is not in trimChars is encountered. Por ejemplo, si la cadena actual es "123abc456xyz789" y trimChars contiene los dígitos de "1" a "9", el TrimStart(System.Char[]) método devuelve "abc456xyz789".For example, if the current string is "123abc456xyz789" and trimChars contains the digits from "1" through "9", the TrimStart(System.Char[]) method returns "abc456xyz789".

Notas a los autores de las llamadas

El .NET Framework 3,5 SP1 y las versiones anteriores mantiene una lista interna de caracteres de espacio en blanco que este método recorta si trimChars es null o una matriz vacía.The .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. A partir de la .NET Framework 4, si trimChars es null o una matriz vacía, el método recorta todos los caracteres de espacio en blanco Unicode (es decir, los caracteres que generan un true valor devuelto cuando se pasan al IsWhiteSpace(Char) método).Starting with the .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). Debido a este cambio, el Trim() método en el .NET Framework 3,5 SP1 y versiones anteriores quita dos caracteres, espacio de ancho cero (u + 200B) y espacio sin interrupción de ancho cero (u + FEFF), que el Trim() método de .NET Framework 4 y versiones posteriores no quita.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 4 and later versions does not remove. Además, el Trim() método en el .NET Framework 3,5 SP1 y versiones anteriores no recorta tres caracteres de espacio en blanco Unicode: SEparador de vocal mongol (u + 180E), espacio de no separación limitado (u + 202F) y espacio matemático medio (u + 205F).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).

Consulte también

• Char
• Trim(Char[])
• TrimEnd(Char[])
• IsWhiteSpace(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

Parámetros

Devoluciones

String

La cadena que queda después de quitar todas las repeticiones del carácter trimChar del inicio de la cadena actual.The string that remains after all occurrences of the trimChar character are removed from the start of the current string. Si no se puede quitar ningún carácter de la instancia actual, el método devuelve la instancia actual sin cambios.If no characters can be trimmed from the current instance, the method returns the current instance unchanged.

Comentarios

El TrimStart(System.Char) método quita todos los caracteres iniciales de la cadena actual trimChar .The TrimStart(System.Char) method removes from the current string all leading trimChar characters. La operación de recorte se detiene cuando se encuentra un carácter que no está trimChar .The trim operation stops when a character that is not trimChar is encountered. Por ejemplo, si trimChar es - y la cadena actual es "---ABC---XYZ----", el TrimStart(System.Char) método devuelve "abc---xyz----".For example, if trimChar is - and the current string is "---abc---xyz----", the TrimStart(System.Char) method returns "abc---xyz----".