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String.ToLower Method (CultureInfo)

Returns a copy of this string converted to lowercase, using the casing rules of the specified culture.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

Public Function ToLower ( _
	culture As CultureInfo _
) As String


Type: System.Globalization.CultureInfo

An object that supplies culture-specific casing rules.

Return Value

Type: System.String
The lowercase equivalent of the current string.


culture is Nothing.

The casing rules of the culture specified by the culture parameter determine the way the case of the string is changed.


This method does not modify the value of the current instance. Instead, it returns a new string in which all characters in the current instance are converted to lowercase.

Security Considerations

If you pass the ToLower(CultureInfo) method a CultureInfo object other than CultureInfo.InvariantCulture, the casing operation will take culture-specific rules into account. 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. This produces the same result in every culture and performs more efficiently.

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. 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) 
Imports System
Imports System.Globalization
Imports Microsoft.VisualBasic

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("str1 = '{0}'", str1)

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

      ' 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("str3 is {0} to str4.", _
                         IIf(0 = [String].CompareOrdinal(str3, str4), "equal", "not equal"))
      CodePoints("str3", str3)
      CodePoints("str4", str4)
   End Sub 'Main

   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
   End Sub 'CodePoints
End Class 'Sample

'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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8
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