String.ToLower
Method
Definition
Overloads
| ToLower() |
Returns a copy of this string converted to lowercase. |
| ToLower(CultureInfo) |
Returns a copy of this string converted to lowercase, using the casing rules of the specified culture. |
ToLower()
Returns a copy of this string converted to lowercase.
public string ToLower ();
A string in lowercase.
Examples
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
Imports System
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
Remarks
This method takes into account the casing rules of the current culture.
Note
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
The casing operation that results from calling the ToLower() method takes the casing conventions of the current culture 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 methods. This produces the same result in every culture (unlike the ToLower() method) and performs more efficiently.
ToLower(CultureInfo)
Returns a copy of this string converted to lowercase, using the casing rules of the specified culture.
public string ToLower (System.Globalization.CultureInfo culture);
- culture
- CultureInfo
An object that supplies culture-specific casing rules.
The lowercase equivalent of the current string.
culture is null.
Examples
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)
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
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()
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 '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
Console.WriteLine()
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
Remarks
The casing rules of the culture specified by the culture parameter determine the way the case of the string is changed.
Note
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.