String.TrimStart Método

Origem:

String.Manipulation.cs

public:
 System::String ^ TrimStart(System::Text::Rune trimRune);

public string TrimStart(System.Text.Rune trimRune);

member this.TrimStart : System.Text.Rune -> string

Public Function TrimStart (trimRune As Rune) As String

Parâmetros

Devoluções

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

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

Parâmetros

Devoluções

A cadeia que permanece após todas as ocorrências de caracteres no trimChars parâmetro serem removidas do início da cadeia atual. Se trimChars for null ou um array vazio, os caracteres de espaço em branco são removidos em vez disso. Se nenhum carácter puder ser cortado da instância atual, o método devolve a instância atual inalterada.

Exemplos

O exemplo seguinte demonstra a funcionalidade básica do TrimStart método:

// 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

// TrimStart examples
let lineWithLeadingSpaces = "   Hello World!"
let lineWithLeadingSymbols = "$$$$Hello World!"
let lineWithLeadingUnderscores = "_____Hello World!"
let lineWithLeadingLetters = "xxxxHello World!"

// Make it easy to print out and work with all of the examples
let lines = [| lineWithLeadingSpaces; lineWithLeadingSymbols; lineWithLeadingUnderscores; lineWithLeadingLetters |]

for line in lines do
    printfn $"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
let lineAfterTrimStart = lineWithLeadingSpaces.TrimStart ' '
printfn $"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 lineToEdit in lines do
    printfn $"""{lineToEdit.TrimStart(' ', '$', '_', 'x')}"""
// Result for each: Hello World!

// or handle pieces of data that have multiple kinds of leading characters 
let lineToBeTrimmed = "__###__ John Smith"
let lineAfterTrimStart2 = lineToBeTrimmed.TrimStart('_', '#', ' ')
printfn $"{lineAfterTrimStart2}"
// 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

O exemplo seguinte utiliza o TrimStart método para cortar espaços em branco e caracteres de comentário de linhas de código-fonte. O método StripComments envolve uma chamada para TrimStart e passa-lhe um array de caracteres que contém um espaço e o carácter de comentário, que é um apóstrofo ( ' ) em Visual Basic e uma barra ( / ) em C# ou F#. O TrimStart método também é chamado para remover espaços em branco iniciais ao avaliar se uma cadeia é um comentário.

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();
}

let stripComments (lines: #seq<string>) =
    [|  for line in lines do
            if line.TrimStart(' ').StartsWith "//" then
                line.TrimStart(' ', '/') |]

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

O exemplo seguinte ilustra então uma chamada ao StripComments método.

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.

let lines = 
    [| "module HelloWorld"
       ""
       "[<EntryPoint>]"
       "let main _ ="
       "    // This code displays a simple greeting"
       "    // to the console."
       "    printfn \"Hello, World.\""
       "    0" |]
printfn "Before call to StripComments:"
for line in lines do
    printfn $"   {line}"

let strippedLines = stripComments lines
printfn "After call to StripComments:"
for line in strippedLines do
    printfn $"   {line}"
// This code produces the following output to the console:
//    Before call to StripComments:
//       module HelloWorld
//
//       [<EntryPoint>]
//       let main _ =
//           // This code displays a simple greeting
//           // to the console.
//           printfn "Hello, World."
//           0
//    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.

Observações

O TrimStart(System.Char[]) método remove da cadeia atual todos os caracteres iniciais que estão no trimChars parâmetro. A operação de corte termina quando se encontra uma personagem que não está presente trimChars . Por exemplo, se a cadeia atual for "123abc456xyz789" e trimChars contiver os dígitos de "1" a "9", o TrimStart(System.Char[]) método devolve "abc456xyz789".

Notas para Chamadores

O .NET Framework 3.5 SP1 e versões anteriores mantém uma lista interna de caracteres em branco que este método elimina se trimChars for null ou um array vazio. A partir do .NET Framework 4, se trimChars for null ou um array vazio, o método corta todos os caracteres em branco Unicode (ou seja, caracteres que produzem um valor de retorno true quando são passados para o método IsWhiteSpace(Char)). Devido a esta alteração, o método Trim() no .NET Framework 3.5 SP1 e versões anteriores remove dois caracteres, ZERO WIDTH SPACE (U+200B) e ZERO WIDTH NO-BREAK SPACE (U+FEFF), que o método Trim() no .NET Framework 4 e versões posteriores não remove. Além disso, o método Trim() no .NET Framework 3.5 SP1 e versões anteriores não elimina três caracteres de espaço em branco Unicode: SEPARADOR VOCÁLICO MONGOL (U+180E), ESPAÇO NO-BREAK ESTREITO (U+202F) e ESPAÇO MATEMÁTICO MÉDIO (U+205F).

Ver também

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

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

public:
 System::String ^ TrimStart(char trimChar);

public string TrimStart(char trimChar);

member this.TrimStart : char -> string

Public Function TrimStart (trimChar As Char) As String

Parâmetros

Devoluções

A cadeia que permanece após todas as ocorrências do trimChar carácter serem removidas do início da sequência atual. Se nenhum carácter puder ser cortado da instância atual, o método devolve a instância atual inalterada.

Observações

O TrimStart(System.Char) método remove da cadeia corrente todos os caracteres iniciais trimChar . A operação de corte termina quando se encontra um carácter que não trimChar está. Por exemplo, se trimChar for - e a cadeia atual for "---abc---xyz----", o TrimStart(System.Char) método devolve "abc---xyz----".

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

Origem:

String.Manipulation.cs

public:
 System::String ^ TrimStart();

public string TrimStart();

member this.TrimStart : unit -> string

Public Function TrimStart () As String

Devoluções

A cadeia que permanece após todos os caracteres de espaço em branco serem removidos do início da cadeia atual. Se nenhum carácter puder ser cortado da instância atual, o método devolve a instância atual inalterada.

Observações

O TrimStart método remove da cadeia corrente todos os caracteres de espaço em branco iniciais. A operação de corte termina quando se encontra um carácter que não está em branco. Por exemplo, se a cadeia atual for " abc xyz ", o TrimStart método devolve "abc xyz ".