CompareInfo.IsPrefix CompareInfo.IsPrefix CompareInfo.IsPrefix CompareInfo.IsPrefix Method

Definição

Determina se uma cadeia de caracteres começa com um prefixo específico.Determines whether a string starts with a specific prefix.

Sobrecargas

IsPrefix(String, String) IsPrefix(String, String) IsPrefix(String, String) IsPrefix(String, String)

Determina se a cadeia de caracteres de origem determinada começa com o prefixo especificado.Determines whether the specified source string starts with the specified prefix.

IsPrefix(String, String, CompareOptions) IsPrefix(String, String, CompareOptions) IsPrefix(String, String, CompareOptions) IsPrefix(String, String, CompareOptions)

Determina se a cadeia de caracteres de origem determinada começa com o prefixo dado usando o valor CompareOptions especificado.Determines whether the specified source string starts with the specified prefix using the specified CompareOptions value.

IsPrefix(String, String) IsPrefix(String, String) IsPrefix(String, String) IsPrefix(String, String)

Determina se a cadeia de caracteres de origem determinada começa com o prefixo especificado.Determines whether the specified source string starts with the specified prefix.

public:
 virtual bool IsPrefix(System::String ^ source, System::String ^ prefix);
public virtual bool IsPrefix (string source, string prefix);
abstract member IsPrefix : string * string -> bool
override this.IsPrefix : string * string -> bool
Public Overridable Function IsPrefix (source As String, prefix As String) As Boolean

Parâmetros

source
String String String String

A cadeia de caracteres a ser pesquisada.The string to search in.

prefix
String String String String

A cadeia de caracteres a ser comparada com o início de source.The string to compare with the beginning of source.

Retornos

true se o tamanho de prefix for menor ou igual ao tamanho de source e source começar com prefix; caso contrário, false.true if the length of prefix is less than or equal to the length of source and source starts with prefix; otherwise, false.

Exceções

source é null.source is null.

- ou --or-

prefix é null.prefix is null.

Exemplos

O exemplo a seguir determina se uma cadeia de caracteres é o prefixo ou sufixo de outra cadeia de caracteres.The following example determines whether a string is the prefix or suffix of another string.

using namespace System;
using namespace System::Globalization;
int main()
{
   
   // Defines the strings to compare.
   String^ myStr1 = "calle";
   String^ myStr2 = "llegar";
   String^ myXfix = "lle";
   
   // Uses the CompareInfo property of the InvariantCulture.
   CompareInfo^ myComp = CultureInfo::InvariantCulture->CompareInfo;
   
   // Determines whether myXfix is a prefix of S"calle" and S"llegar".
   Console::WriteLine( "IsPrefix( {0}, {1}) : {2}", myStr1, myXfix, myComp->IsPrefix( myStr1, myXfix ) );
   Console::WriteLine( "IsPrefix( {0}, {1}) : {2}", myStr2, myXfix, myComp->IsPrefix( myStr2, myXfix ) );
   
   // Determines whether myXfix is a suffix of S"calle" and S"llegar".
   Console::WriteLine( "IsSuffix( {0}, {1}) : {2}", myStr1, myXfix, myComp->IsSuffix( myStr1, myXfix ) );
   Console::WriteLine( "IsSuffix( {0}, {1}) : {2}", myStr2, myXfix, myComp->IsSuffix( myStr2, myXfix ) );
}

/*
This code produces the following output.

IsPrefix(calle, lle) : False
IsPrefix(llegar, lle) : True
IsSuffix(calle, lle) : True
IsSuffix(llegar, lle) : False

*/
using System;
using System.Globalization;

public class SamplesCompareInfo  {

   public static void Main()  {

      // Defines the strings to compare.
      String myStr1 = "calle";
      String myStr2 = "llegar";
      String myXfix = "lle";

      // Uses the CompareInfo property of the InvariantCulture.
      CompareInfo myComp = CultureInfo.InvariantCulture.CompareInfo;

      // Determines whether myXfix is a prefix of "calle" and "llegar".
      Console.WriteLine( "IsPrefix( {0}, {1} ) : {2}", myStr1, myXfix, myComp.IsPrefix( myStr1, myXfix ) );
      Console.WriteLine( "IsPrefix( {0}, {1} ) : {2}", myStr2, myXfix, myComp.IsPrefix( myStr2, myXfix ) );

      // Determines whether myXfix is a suffix of "calle" and "llegar".
      Console.WriteLine( "IsSuffix( {0}, {1} ) : {2}", myStr1, myXfix, myComp.IsSuffix( myStr1, myXfix ) );
      Console.WriteLine( "IsSuffix( {0}, {1} ) : {2}", myStr2, myXfix, myComp.IsSuffix( myStr2, myXfix ) );

   }

}


/*
This code produces the following output.

IsPrefix( calle, lle ) : False
IsPrefix( llegar, lle ) : True
IsSuffix( calle, lle ) : True
IsSuffix( llegar, lle ) : False

*/
Imports System.Globalization

Public Class SamplesCompareInfo

   Public Shared Sub Main()

      ' Defines the strings to compare.
      Dim myStr1 As [String] = "calle"
      Dim myStr2 As [String] = "llegar"
      Dim myXfix As [String] = "lle"

      ' Uses the CompareInfo property of the InvariantCulture.
      Dim myComp As CompareInfo = CultureInfo.InvariantCulture.CompareInfo

      ' Determines whether myXfix is a prefix of "calle" and "llegar".
      Console.WriteLine("IsPrefix( {0}, {1} ) : {2}", myStr1, myXfix, myComp.IsPrefix(myStr1, myXfix))
      Console.WriteLine("IsPrefix( {0}, {1} ) : {2}", myStr2, myXfix, myComp.IsPrefix(myStr2, myXfix))

      ' Determines whether myXfix is a suffix of "calle" and "llegar".
      Console.WriteLine("IsSuffix( {0}, {1} ) : {2}", myStr1, myXfix, myComp.IsSuffix(myStr1, myXfix))
      Console.WriteLine("IsSuffix( {0}, {1} ) : {2}", myStr2, myXfix, myComp.IsSuffix(myStr2, myXfix))

   End Sub 'Main 

End Class 'SamplesCompareInfo


'This code produces the following output.
'
'IsPrefix( calle, lle ) : False
'IsPrefix( llegar, lle ) : True
'IsSuffix( calle, lle ) : True
'IsSuffix( llegar, lle ) : False

Comentários

Cada cadeia de caracteres começa e termina com uma subcadeia de caracteres vazia (""); Portanto, se prefix for uma cadeia de caracteres vazia, esse truemétodo retornará.Every string starts and ends with an empty substring (""); therefore, if prefix is an empty string, this method returns true.

Observação

Quando possível, você deve chamar métodos de comparação de cadeia de caracteres que têm CompareOptions um parâmetro do tipo para especificar o tipo de comparação esperado.When possible, you should call string comparison methods that have a parameter of type CompareOptions to specify the kind of comparison expected. Como regra geral, use as opções linguísticas (usando a cultura atual) para comparar as cadeias de caracteres exibidas na CompareOptions.Ordinal interface CompareOptions.OrdinalIgnoreCase do usuário e especificar ou para comparações de segurança.As a general rule, use linguistic options (using the current culture) for comparing strings displayed in the user interface and specify CompareOptions.Ordinal or CompareOptions.OrdinalIgnoreCase for security comparisons.

Veja também

IsPrefix(String, String, CompareOptions) IsPrefix(String, String, CompareOptions) IsPrefix(String, String, CompareOptions) IsPrefix(String, String, CompareOptions)

Determina se a cadeia de caracteres de origem determinada começa com o prefixo dado usando o valor CompareOptions especificado.Determines whether the specified source string starts with the specified prefix using the specified CompareOptions value.

public:
 virtual bool IsPrefix(System::String ^ source, System::String ^ prefix, System::Globalization::CompareOptions options);
public virtual bool IsPrefix (string source, string prefix, System.Globalization.CompareOptions options);
abstract member IsPrefix : string * string * System.Globalization.CompareOptions -> bool
override this.IsPrefix : string * string * System.Globalization.CompareOptions -> bool
Public Overridable Function IsPrefix (source As String, prefix As String, options As CompareOptions) As Boolean

Parâmetros

source
String String String String

A cadeia de caracteres a ser pesquisada.The string to search in.

prefix
String String String String

A cadeia de caracteres a ser comparada com o início de source.The string to compare with the beginning of source.

options
CompareOptions CompareOptions CompareOptions CompareOptions

Um valor que define como source e prefix devem ser comparados.A value that defines how source and prefix should be compared. options é o valor de enumeração Ordinal ou uma combinação bit a bit de um ou mais dos seguintes valores: IgnoreCase, IgnoreSymbols, IgnoreNonSpace, IgnoreWidth e IgnoreKanaType.options is either the enumeration value Ordinal, or a bitwise combination of one or more of the following values: IgnoreCase, IgnoreSymbols, IgnoreNonSpace, IgnoreWidth, and IgnoreKanaType.

Retornos

true se o tamanho de prefix for menor ou igual ao tamanho de source e source começar com prefix; caso contrário, false.true if the length of prefix is less than or equal to the length of source and source starts with prefix; otherwise, false.

Exceções

source é null.source is null.

- ou --or-

prefix é null.prefix is null.

options contém um valor CompareOptions inválido.options contains an invalid CompareOptions value.

Exemplos

O exemplo a seguir determina se uma cadeia de caracteres é o prefixo ou sufixo de CompareOptionsoutra cadeia de caracteres usando.The following example determines whether a string is the prefix or suffix of another string using CompareOptions.

using namespace System;
using namespace System::Globalization;
int main()
{
   
   // Defines the strings to compare.
   String^ myStr1 = "calle";
   String^ myStr2 = "llegar";
   String^ myXfix = "LLE";
   
   // Uses the CompareInfo property of the InvariantCulture.
   CompareInfo^ myComp = CultureInfo::InvariantCulture->CompareInfo;
   Console::WriteLine( "IsSuffix \"{0}\", \"{1}\"", myStr1, myXfix );
   Console::WriteLine( "   With no CompareOptions            : {0}", myComp->IsSuffix( myStr1, myXfix ) );
   Console::WriteLine( "   With None                         : {0}", myComp->IsSuffix( myStr1, myXfix, CompareOptions::None ) );
   Console::WriteLine( "   With Ordinal                      : {0}", myComp->IsSuffix( myStr1, myXfix, CompareOptions::Ordinal ) );
   Console::WriteLine( "   With IgnoreCase                   : {0}", myComp->IsSuffix( myStr1, myXfix, CompareOptions::IgnoreCase ) );
   Console::WriteLine( "IsPrefix \"{0}\", \"{1}\"", myStr2, myXfix );
   Console::WriteLine( "   With no CompareOptions            : {0}", myComp->IsPrefix( myStr2, myXfix ) );
   Console::WriteLine( "   With None                         : {0}", myComp->IsPrefix( myStr2, myXfix, CompareOptions::None ) );
   Console::WriteLine( "   With Ordinal                      : {0}", myComp->IsPrefix( myStr2, myXfix, CompareOptions::Ordinal ) );
   Console::WriteLine( "   With IgnoreCase                   : {0}", myComp->IsPrefix( myStr2, myXfix, CompareOptions::IgnoreCase ) );
}

/*
This code produces the following output.

IsSuffix "calle", "LLE"
   With no CompareOptions            : False
   With None                         : False
   With Ordinal                      : False
   With IgnoreCase                   : True
IsPrefix "llegar", "LLE"
   With no CompareOptions            : False
   With None                         : False
   With Ordinal                      : False
   With IgnoreCase                   : True
*/
using System;
using System.Globalization;

public class SamplesCompareInfo  {

   public static void Main()  {

      // Defines the strings to compare.
      String myStr1 = "calle";
      String myStr2 = "llegar";
      String myXfix = "LLE";

      // Uses the CompareInfo property of the InvariantCulture.
      CompareInfo myComp = CultureInfo.InvariantCulture.CompareInfo;

      Console.WriteLine( "IsSuffix \"{0}\", \"{1}\"", myStr1, myXfix );
      Console.WriteLine( "   With no CompareOptions            : {0}", myComp.IsSuffix( myStr1, myXfix ) );
      Console.WriteLine( "   With None                         : {0}", myComp.IsSuffix( myStr1, myXfix, CompareOptions.None ) );
      Console.WriteLine( "   With Ordinal                      : {0}", myComp.IsSuffix( myStr1, myXfix, CompareOptions.Ordinal ) );
      Console.WriteLine( "   With IgnoreCase                   : {0}", myComp.IsSuffix( myStr1, myXfix, CompareOptions.IgnoreCase ) );

      Console.WriteLine( "IsPrefix \"{0}\", \"{1}\"", myStr2, myXfix );
      Console.WriteLine( "   With no CompareOptions            : {0}", myComp.IsPrefix( myStr2, myXfix ) );
      Console.WriteLine( "   With None                         : {0}", myComp.IsPrefix( myStr2, myXfix, CompareOptions.None ) );
      Console.WriteLine( "   With Ordinal                      : {0}", myComp.IsPrefix( myStr2, myXfix, CompareOptions.Ordinal ) );
      Console.WriteLine( "   With IgnoreCase                   : {0}", myComp.IsPrefix( myStr2, myXfix, CompareOptions.IgnoreCase ) );

   }

}


/*
This code produces the following output.

IsSuffix "calle", "LLE"
   With no CompareOptions            : False
   With None                         : False
   With Ordinal                      : False
   With IgnoreCase                   : True
IsPrefix "llegar", "LLE"
   With no CompareOptions            : False
   With None                         : False
   With Ordinal                      : False
   With IgnoreCase                   : True

*/
Imports System.Globalization

Public Class SamplesCompareInfo

   Public Shared Sub Main()

      ' Defines the strings to compare.
      Dim myStr1 As [String] = "calle"
      Dim myStr2 As [String] = "llegar"
      Dim myXfix As [String] = "LLE"

      ' Uses the CompareInfo property of the InvariantCulture.
      Dim myComp As CompareInfo = CultureInfo.InvariantCulture.CompareInfo

      Console.WriteLine("IsSuffix ""{0}"", ""{1}""", myStr1, myXfix)
      Console.WriteLine("   With no CompareOptions            : {0}", myComp.IsSuffix(myStr1, myXfix))
      Console.WriteLine("   With None                         : {0}", myComp.IsSuffix(myStr1, myXfix, CompareOptions.None))
      Console.WriteLine("   With Ordinal                      : {0}", myComp.IsSuffix(myStr1, myXfix, CompareOptions.Ordinal))
      Console.WriteLine("   With IgnoreCase                   : {0}", myComp.IsSuffix(myStr1, myXfix, CompareOptions.IgnoreCase))

      Console.WriteLine("IsPrefix ""{0}"", ""{1}""", myStr2, myXfix)
      Console.WriteLine("   With no CompareOptions            : {0}", myComp.IsPrefix(myStr2, myXfix))
      Console.WriteLine("   With None                         : {0}", myComp.IsPrefix(myStr2, myXfix, CompareOptions.None))
      Console.WriteLine("   With Ordinal                      : {0}", myComp.IsPrefix(myStr2, myXfix, CompareOptions.Ordinal))
      Console.WriteLine("   With IgnoreCase                   : {0}", myComp.IsPrefix(myStr2, myXfix, CompareOptions.IgnoreCase))

   End Sub 'Main 

End Class 'SamplesCompareInfo


'This code produces the following output.
'
'IsSuffix "calle", "LLE"
'   With no CompareOptions            : False
'   With None                         : False
'   With Ordinal                      : False
'   With IgnoreCase                   : True
'IsPrefix "llegar", "LLE"
'   With no CompareOptions            : False
'   With None                         : False
'   With Ordinal                      : False
'   With IgnoreCase                   : True

Comentários

Cada cadeia de caracteres começa e termina com uma subcadeia de caracteres vazia (""); Portanto, se prefix for uma cadeia de caracteres vazia, esse truemétodo retornará.Every string starts and ends with an empty substring (""); therefore, if prefix is an empty string, this method returns true.

O CompareOptions.StringSort valor não é válido para este método.The CompareOptions.StringSort value is not valid for this method.

Observação

Quando possível, você deve chamar métodos de comparação de cadeia de caracteres que têm CompareOptions um parâmetro do tipo para especificar o tipo de comparação esperado.When possible, you should call string comparison methods that have a parameter of type CompareOptions to specify the kind of comparison expected. Como regra geral, use as opções linguísticas (usando a cultura atual) para comparar as cadeias de caracteres exibidas na CompareOptions.Ordinal interface CompareOptions.OrdinalIgnoreCase do usuário e especificar ou para comparações de segurança.As a general rule, use linguistic options (using the current culture) for comparing strings displayed in the user interface and specify CompareOptions.Ordinal or CompareOptions.OrdinalIgnoreCase for security comparisons.

Veja também

Aplica-se a