String.ToLower メソッド

定義

この文字列のコピーを小文字に変換して返します。Returns a copy of this string converted to lowercase.

オーバーロード

ToLower(CultureInfo)

指定されたカルチャの大文字と小文字の規則を使用して、この文字列のコピーを小文字に変換して返します。Returns a copy of this string converted to lowercase, using the casing rules of the specified culture.

ToLower()

この文字列のコピーを小文字に変換して返します。Returns a copy of this string converted to lowercase.

ToLower(CultureInfo)

指定されたカルチャの大文字と小文字の規則を使用して、この文字列のコピーを小文字に変換して返します。Returns a copy of this string converted to lowercase, using the casing rules of the specified culture.

public:
 System::String ^ ToLower(System::Globalization::CultureInfo ^ culture);
public string ToLower (System.Globalization.CultureInfo culture);
member this.ToLower : System.Globalization.CultureInfo -> string
Public Function ToLower (culture As CultureInfo) As String

パラメーター

culture
CultureInfo

カルチャ固有の大文字と小文字の規則を提供するオブジェクト。An object that supplies culture-specific casing rules.

戻り値

現在の文字列を小文字にしたもの。The lowercase equivalent of the current string.

例外

culturenullです。culture is null.

次の例では、大文字の2つの文字列を、英語 (米国) とトルコ語 (トルコ) のカルチャを使用して小文字に変換し、その後、小文字の文字列を比較します。The following example converts two strings of uppercase characters to lowercase characters using the English-United States and Turkish-Turkey cultures, then compares the lowercase strings. 大文字の文字列は同じですが、1つの文字列に Unicode ラテン大文字 I が出現するたびに、もう一方の文字列には上記のドット付きのラテン大文字 I が含まれている点が異なります。The uppercase strings are identical except that for each occurrence of the Unicode LATIN CAPITAL LETTER I in one string, the other string contains LATIN CAPITAL LETTER I WITH DOT ABOVE.

// Sample for String::ToLower(CultureInfo)
using namespace System;
using namespace System::Globalization;
void CodePoints( String^ title, String^ s )
{
   Console::Write( "{0}The code points in {1} are: {0}", Environment::NewLine, title );
   System::Collections::IEnumerator^ myEnum = s->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      UInt16 u =  safe_cast<Char>(myEnum->Current);
      Console::Write( "{0:x4} ", u );
   }

   Console::WriteLine();
}

int main()
{
   String^ str1 = "INDIGO";
   
   // str2 = str1, except each 'I' is '\u0130' (Unicode LATIN CAPITAL I WITH DOT ABOVE).
   array<Char>^temp = {L'\u0130',L'N',L'D',L'\u0130',L'G',L'O'};
   String^ str2 = gcnew String( temp );
   String^ str3;
   String^ str4;
   Console::WriteLine();
   Console::WriteLine( "str1 = '{0}'", str1 );
   Console::WriteLine();
   Console::WriteLine( "str1 is {0} to str2.", ((0 == String::CompareOrdinal( str1, str2 )) ? (String^)"equal" : "not equal") );
   CodePoints( "str1", str1 );
   CodePoints( "str2", str2 );
   Console::WriteLine();
   
   // str3 is a lower case copy of str2, using English-United States culture.
   Console::WriteLine( "str3 = Lower case copy of str2 using English-United States culture." );
   str3 = str2->ToLower( gcnew CultureInfo( "en-US",false ) );
   
   // str4 is a lower case copy of str2, using Turkish-Turkey culture.
   Console::WriteLine( "str4 = Lower case copy of str2 using Turkish-Turkey culture." );
   str4 = str2->ToLower( gcnew CultureInfo( "tr-TR",false ) );
   
   // Compare the code points in str3 and str4.
   Console::WriteLine();
   Console::WriteLine( "str3 is {0} to str4.", ((0 == String::CompareOrdinal( str3, str4 )) ? (String^)"equal" : "not equal") );
   CodePoints( "str3", str3 );
   CodePoints( "str4", str4 );
}

/*
This example produces the following results:

str1 = 'INDIGO'

str1 is not equal to str2.

The code points in str1 are:
0049 004e 0044 0049 0047 004f

The code points in str2 are:
0130 004e 0044 0130 0047 004f

str3 = Lower case copy of str2 using English-United States culture.
str4 = Lower case copy of str2 using Turkish-Turkey culture.

str3 is equal to str4.

The code points in str3 are:
0069 006e 0064 0069 0067 006f

The code points in str4 are:
0069 006e 0064 0069 0067 006f
*/
// Sample for String.ToLower(CultureInfo)

using System;
using System.Globalization;

class Sample 
{
    public static void Main() 
    {
    String str1 = "INDIGO";
    // str2 = str1, except each 'I' is '\u0130' (Unicode LATIN CAPITAL I WITH DOT ABOVE).
    String str2 = new String(new Char[] {'\u0130', 'N', 'D', '\u0130', 'G', 'O'});
    String str3, str4;

    Console.WriteLine();
    Console.WriteLine("str1 = '{0}'", str1);

    Console.WriteLine();
    Console.WriteLine("str1 is {0} to str2.", 
         ((0 == String.CompareOrdinal(str1, str2)) ? "equal" : "not equal"));
    CodePoints("str1", str1);
    CodePoints("str2", str2);

    Console.WriteLine();
    // str3 is a lower case copy of str2, using English-United States culture.
    Console.WriteLine("str3 = Lower case copy of str2 using English-United States culture.");
    str3 = str2.ToLower(new CultureInfo("en-US", false));

    // str4 is a lower case copy of str2, using Turkish-Turkey culture.
    Console.WriteLine("str4 = Lower case copy of str2 using Turkish-Turkey culture.");
    str4 = str2.ToLower(new CultureInfo("tr-TR", false));

    // Compare the code points in str3 and str4.
    Console.WriteLine();
    Console.WriteLine("str3 is {0} to str4.", 
         ((0 == String.CompareOrdinal(str3, str4)) ? "equal" : "not equal"));
    CodePoints("str3", str3);
    CodePoints("str4", str4);
    }

    public static void CodePoints(String title, String s)
    {
    Console.Write("{0}The code points in {1} are: {0}", Environment.NewLine, title);
    foreach (ushort u in s)
      Console.Write("{0:x4} ", u);
    Console.WriteLine();
    }
}
/*
This example produces the following results:

str1 = 'INDIGO'

str1 is not equal to str2.

The code points in str1 are:
0049 004e 0044 0049 0047 004f

The code points in str2 are:
0130 004e 0044 0130 0047 004f

str3 = Lower case copy of str2 using English-United States culture.
str4 = Lower case copy of str2 using Turkish-Turkey culture.

str3 is equal to str4.

The code points in str3 are:
0069 006e 0064 0069 0067 006f

The code points in str4 are:
0069 006e 0064 0069 0067 006f
*/
' Sample for String.ToLower(CultureInfo)
Imports System.Globalization

Class Sample
   Public Shared Sub Main()
      Dim str1 As [String] = "INDIGO"
      ' str2 = str1, except each 'I' is '\u0130' (Unicode LATIN CAPITAL I WITH DOT ABOVE).
      Dim str2 As New [String](New [Char]() {ChrW(&H0130), "N"c, "D"c, ChrW(&H0130), "G"c, "O"c})
      Dim str3, str4 As [String]

      Console.WriteLine()
      Console.WriteLine("str1 = '{0}'", str1)

      Console.WriteLine()
      Console.WriteLine("str1 is {0} to str2.", _
                         IIf(0 = [String].CompareOrdinal(str1, str2), "equal", "not equal"))
      CodePoints("str1", str1)
      CodePoints("str2", str2)

      Console.WriteLine()
      ' str3 is a lower case copy of str2, using English-United States culture.
      Console.WriteLine("str3 = Lower case copy of str2 using English-United States culture.")
      str3 = str2.ToLower(New CultureInfo("en-US", False))

      ' str4 is a lower case copy of str2, using Turkish-Turkey culture.
      Console.WriteLine("str4 = Lower case copy of str2 using Turkish-Turkey culture.")
      str4 = str2.ToLower(New CultureInfo("tr-TR", False))

      ' Compare the code points in str3 and str4.
      Console.WriteLine()
      Console.WriteLine("str3 is {0} to str4.", _
                         IIf(0 = [String].CompareOrdinal(str3, str4), "equal", "not equal"))
      CodePoints("str3", str3)
      CodePoints("str4", str4)
   End Sub

   Public Shared Sub CodePoints(title As [String], s As [String])
      Console.Write("{0}The code points in {1} are: {0}", Environment.NewLine, title)
      Dim c As Char
      For Each c In  s
         Console.Write("{0:x4} ", AscW(c))
      Next c
      Console.WriteLine()
   End Sub
End Class
'
'str1 = 'INDIGO'
'
'str1 is not equal to str2.
'
'The code points in str1 are:
'0049 004e 0044 0049 0047 004f
'
'The code points in str2 are:
'0130 004e 0044 0130 0047 004f
'
'str3 = Lower case copy of str2 using English-United States culture.
'str4 = Lower case copy of str2 using Turkish-Turkey culture.
'
'str3 is equal to str4.
'
'The code points in str3 are:
'0069 006e 0064 0069 0067 006f
'
'The code points in str4 are:
'0069 006e 0064 0069 0067 006f

注釈

culture パラメーターによって指定されたカルチャの大文字と小文字の規則によって、文字列の大文字と小文字の変更方法が決まります。The casing rules of the culture specified by the culture parameter determine the way the case of the string is changed.

注意

このメソッドは、現在のインスタンスの値を変更しません。This method does not modify the value of the current instance. 代わりに、現在のインスタンス内のすべての文字が小文字に変換される新しい文字列が返されます。Instead, it returns a new string in which all characters in the current instance are converted to lowercase.

セキュリティの考慮事項Security Considerations

ToLower(CultureInfo) メソッドに CultureInfo.InvariantCulture以外の CultureInfo オブジェクトを渡すと、大文字と小文字の操作によってカルチャ固有の規則が考慮されます。If you pass the ToLower(CultureInfo) method a CultureInfo object other than CultureInfo.InvariantCulture, the casing operation will take culture-specific rules into account. ファイル名、名前付きパイプ、レジストリキーなど、オペレーティングシステム識別子の小文字または大文字のバージョンが必要な場合は、ToLowerInvariant または ToUpperInvariant のいずれかの方法を使用します。If you need the lowercase or uppercase version of an operating system identifier, such as a file name, named pipe, or registry key, use the ToLowerInvariant or ToUpperInvariant method. これにより、すべてのカルチャで同じ結果が生成され、より効率的に実行されます。This produces the same result in every culture and performs more efficiently.

こちらもご覧ください

ToLower()

この文字列のコピーを小文字に変換して返します。Returns a copy of this string converted to lowercase.

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

戻り値

小文字の文字列。A string in lowercase.

次の例では、複数の大文字と小文字が混在する文字列を小文字に変換します。The following example converts several mixed case strings to lowercase.

using namespace System;
using namespace System::Collections;
int main()
{
   array<String^>^info = {"Name","Title","Age","Location","Gender"};
   Console::WriteLine( "The initial values in the array are:" );
   IEnumerator^ myEnum = info->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      String^ s = safe_cast<String^>(myEnum->Current);
      Console::WriteLine( s );
   }

   Console::WriteLine( " {0}The lowercase of these values is:", Environment::NewLine );
   IEnumerator^ myEnum1 = info->GetEnumerator();
   while ( myEnum1->MoveNext() )
   {
      String^ s = safe_cast<String^>(myEnum1->Current);
      Console::WriteLine( s->ToLower() );
   }

   Console::WriteLine( " {0}The uppercase of these values is:", Environment::NewLine );
   IEnumerator^ myEnum2 = info->GetEnumerator();
   while ( myEnum2->MoveNext() )
   {
      String^ s = safe_cast<String^>(myEnum2->Current);
      Console::WriteLine( s->ToUpper() );
   }
}
// The example displays the following output:
//       The initial values in the array are:
//       Name
//       Title
//       Age
//       Location
//       Gender
//       
//       The lowercase of these values is:
//       name
//       title
//       age
//       location
//       gender
//       
//       The uppercase of these values is:
//       NAME
//       TITLE
//       AGE
//       LOCATION
//       GENDER
using System;

public class ToLowerTest {
    public static void Main() {

        string [] info = {"Name", "Title", "Age", "Location", "Gender"};

        Console.WriteLine("The initial values in the array are:");
        foreach (string s in info)
            Console.WriteLine(s);

        Console.WriteLine("{0}The lowercase of these values is:", Environment.NewLine);        

        foreach (string s in info)
            Console.WriteLine(s.ToLower());

        Console.WriteLine("{0}The uppercase of these values is:", Environment.NewLine);        

        foreach (string s in info)
            Console.WriteLine(s.ToUpper());
    }
}
// The example displays the following output:
//       The initial values in the array are:
//       Name
//       Title
//       Age
//       Location
//       Gender
//       
//       The lowercase of these values is:
//       name
//       title
//       age
//       location
//       gender
//       
//       The uppercase of these values is:
//       NAME
//       TITLE
//       AGE
//       LOCATION
//       GENDER
Public Class ToLowerTest
    
    Public Shared Sub Main()
        Dim info As String() = {"Name", "Title", "Age", "Location", "Gender"}
        
        Console.WriteLine("The initial values in the array are:")

        Dim s As String
        For Each s In info
            Console.WriteLine(s)
        Next 

        Console.WriteLine("{0}The lowercase of these values is:", Environment.NewLine)

        For Each s In info
            Console.WriteLine(s.ToLower())
        Next 

        Console.WriteLine("{0}The uppercase of these values is:", Environment.NewLine)

        For Each s In  info
            Console.WriteLine(s.ToUpper())
        Next 
    End Sub 
End Class 
' The example displays the following output:
'       The initial values in the array are:
'       Name
'       Title
'       Age
'       Location
'       Gender
'       
'       The lowercase of these values is:
'       name
'       title
'       age
'       location
'       gender
'       
'       The uppercase of these values is:
'       NAME
'       TITLE
'       AGE
'       LOCATION
'       GENDER

注釈

このメソッドは、現在のカルチャの大文字と小文字の規則を考慮します。This method takes into account the casing rules of the current culture.

注意

このメソッドは、現在のインスタンスの値を変更しません。This method does not modify the value of the current instance. 代わりに、現在のインスタンス内のすべての文字が小文字に変換される新しい文字列が返されます。Instead, it returns a new string in which all characters in the current instance are converted to lowercase.

セキュリティの考慮事項Security Considerations

ToLower() メソッドを呼び出すことによって生成される大文字と小文字の演算では、現在のカルチャの大文字と小文字の表記規則が考慮されます。The casing operation that results from calling the ToLower() method takes the casing conventions of the current culture into account. ファイル名、名前付きパイプ、レジストリキーなど、オペレーティングシステム識別子の小文字または大文字のバージョンが必要な場合は、ToLowerInvariant または ToUpperInvariant のいずれかの方法を使用します。If you need the lowercase or uppercase version of an operating system identifier, such as a file name, named pipe, or registry key, use the ToLowerInvariant or ToUpperInvariant methods. これにより、すべてのカルチャで (ToLower() メソッドとは異なり) 同じ結果が生成され、より効率的に実行されます。This produces the same result in every culture (unlike the ToLower() method) and performs more efficiently.

注意 (呼び出し元)

文字列を使用するためのベストプラクティス」で説明されているように、既定値を置き換える文字列の大文字と小文字の使い分けメソッドを呼び出さずに、パラメーターを明示的に指定する必要があるメソッドを呼び出すことをお勧めします。As explained in Best Practices for Using Strings, we recommend that you avoid calling string casing methods that substitute default values and instead call methods that require parameters to be explicitly specified. 現在のカルチャの大文字小文字の表記規則を使用して文字を小文字に変換するには、culture パラメーターに対して CurrentCulture の値を指定して ToLower(CultureInfo) メソッドオーバーロードを呼び出します。To convert a character to lowercase by using the casing conventions of the current culture, call the ToLower(CultureInfo) method overload with a value of CurrentCulture for its culture parameter.

こちらもご覧ください

適用対象