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String.ToUpper Method

Updated: May 2010

Returns a copy of this String converted to uppercase, using the casing rules of the current culture.

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

public string ToUpper()

Return Value

Type: System.String
A String in uppercase.

This method takes into account the current culture. For more information, see the CultureInfo topic.

NoteNote:

   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 uppercased.

Security Considerations

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.

The following example calls the ToUpper method to convert a series of one-character strings that contain each character in the Basic Latin, Latin-1 Supplement, and Latin Extended-A character sets. It then displays each string whose uppercase character is different from its lowercase character.

using System;

public class Example
{
   public static void Main()
   {
      int n = 0;
      for (int ctr = 0x20; ctr <= 0x017F; ctr++) {
         string string1 = Convert.ToChar(ctr).ToString();
         string upperString = string1.ToUpper();
         if (string1 != upperString) {
            Console.Write(@"{0} (\u+{1}) --> {2} (\u+{3})         ", 
                          string1, 
                          Convert.ToUInt16(string1[0]).ToString("X4"),  
                          upperString, 
                          Convert.ToUInt16(upperString[0]).ToString("X4"));                     
            n++;
            if (n % 2 == 0) Console.WriteLine();
         }
      } 
   }
}
// The example displays the following output: 
//    a (\u+0061) --> A (\u+0041)         b (\u+0062) --> B (\u+0042) 
//    c (\u+0063) --> C (\u+0043)         d (\u+0064) --> D (\u+0044) 
//    e (\u+0065) --> E (\u+0045)         f (\u+0066) --> F (\u+0046) 
//    g (\u+0067) --> G (\u+0047)         h (\u+0068) --> H (\u+0048) 
//    i (\u+0069) --> I (\u+0049)         j (\u+006A) --> J (\u+004A) 
//    k (\u+006B) --> K (\u+004B)         l (\u+006C) --> L (\u+004C) 
//    m (\u+006D) --> M (\u+004D)         n (\u+006E) --> N (\u+004E) 
//    o (\u+006F) --> O (\u+004F)         p (\u+0070) --> P (\u+0050) 
//    q (\u+0071) --> Q (\u+0051)         r (\u+0072) --> R (\u+0052) 
//    s (\u+0073) --> S (\u+0053)         t (\u+0074) --> T (\u+0054) 
//    u (\u+0075) --> U (\u+0055)         v (\u+0076) --> V (\u+0056) 
//    w (\u+0077) --> W (\u+0057)         x (\u+0078) --> X (\u+0058) 
//    y (\u+0079) --> Y (\u+0059)         z (\u+007A) --> Z (\u+005A) 
//    à (\u+00E0) --> À (\u+00C0)         á (\u+00E1) --> Á (\u+00C1) 
//    â (\u+00E2) --> Â (\u+00C2)         ã (\u+00E3) --> Ã (\u+00C3) 
//    ä (\u+00E4) --> Ä (\u+00C4)         å (\u+00E5) --> Å (\u+00C5) 
//    æ (\u+00E6) --> Æ (\u+00C6)         ç (\u+00E7) --> Ç (\u+00C7) 
//    è (\u+00E8) --> È (\u+00C8)         é (\u+00E9) --> É (\u+00C9) 
//    ê (\u+00EA) --> Ê (\u+00CA)         ë (\u+00EB) --> Ë (\u+00CB) 
//    ì (\u+00EC) --> Ì (\u+00CC)         í (\u+00ED) --> Í (\u+00CD) 
//    î (\u+00EE) --> Î (\u+00CE)         ï (\u+00EF) --> Ï (\u+00CF) 
//    ð (\u+00F0) --> Ð (\u+00D0)         ñ (\u+00F1) --> Ñ (\u+00D1) 
//    ò (\u+00F2) --> Ò (\u+00D2)         ó (\u+00F3) --> Ó (\u+00D3) 
//    ô (\u+00F4) --> Ô (\u+00D4)         õ (\u+00F5) --> Õ (\u+00D5) 
//    ö (\u+00F6) --> Ö (\u+00D6)         ø (\u+00F8) --> Ø (\u+00D8) 
//    ù (\u+00F9) --> Ù (\u+00D9)         ú (\u+00FA) --> Ú (\u+00DA) 
//    û (\u+00FB) --> Û (\u+00DB)         ü (\u+00FC) --> Ü (\u+00DC) 
//    ý (\u+00FD) --> Ý (\u+00DD)         þ (\u+00FE) --> Þ (\u+00DE) 
//    ÿ (\u+00FF) --> Ÿ (\u+0178)         ā (\u+0101) --> Ā (\u+0100) 
//    ă (\u+0103) --> Ă (\u+0102)         ą (\u+0105) --> Ą (\u+0104) 
//    ć (\u+0107) --> Ć (\u+0106)         ĉ (\u+0109) --> Ĉ (\u+0108) 
//    ċ (\u+010B) --> Ċ (\u+010A)         č (\u+010D) --> Č (\u+010C) 
//    ď (\u+010F) --> Ď (\u+010E)         đ (\u+0111) --> Đ (\u+0110) 
//    ē (\u+0113) --> Ē (\u+0112)         ĕ (\u+0115) --> Ĕ (\u+0114) 
//    ė (\u+0117) --> Ė (\u+0116)         ę (\u+0119) --> Ę (\u+0118) 
//    ě (\u+011B) --> Ě (\u+011A)         ĝ (\u+011D) --> Ĝ (\u+011C) 
//    ğ (\u+011F) --> Ğ (\u+011E)         ġ (\u+0121) --> Ġ (\u+0120) 
//    ģ (\u+0123) --> Ģ (\u+0122)         ĥ (\u+0125) --> Ĥ (\u+0124) 
//    ħ (\u+0127) --> Ħ (\u+0126)         ĩ (\u+0129) --> Ĩ (\u+0128) 
//    ī (\u+012B) --> Ī (\u+012A)         ĭ (\u+012D) --> Ĭ (\u+012C) 
//    į (\u+012F) --> Į (\u+012E)         ı (\u+0131) --> I (\u+0049) 
//    ij (\u+0133) --> IJ (\u+0132)         ĵ (\u+0135) --> Ĵ (\u+0134) 
//    ķ (\u+0137) --> Ķ (\u+0136)         ĺ (\u+013A) --> Ĺ (\u+0139) 
//    ļ (\u+013C) --> Ļ (\u+013B)         ľ (\u+013E) --> Ľ (\u+013D) 
//    ŀ (\u+0140) --> Ŀ (\u+013F)         ł (\u+0142) --> Ł (\u+0141) 
//    ń (\u+0144) --> Ń (\u+0143)         ņ (\u+0146) --> Ņ (\u+0145) 
//    ň (\u+0148) --> Ň (\u+0147)         ŋ (\u+014B) --> Ŋ (\u+014A) 
//    ō (\u+014D) --> Ō (\u+014C)         ŏ (\u+014F) --> Ŏ (\u+014E) 
//    ő (\u+0151) --> Ő (\u+0150)         œ (\u+0153) --> Œ (\u+0152) 
//    ŕ (\u+0155) --> Ŕ (\u+0154)         ŗ (\u+0157) --> Ŗ (\u+0156) 
//    ř (\u+0159) --> Ř (\u+0158)         ś (\u+015B) --> Ś (\u+015A) 
//    ŝ (\u+015D) --> Ŝ (\u+015C)         ş (\u+015F) --> Ş (\u+015E) 
//    š (\u+0161) --> Š (\u+0160)         ţ (\u+0163) --> Ţ (\u+0162) 
//    ť (\u+0165) --> Ť (\u+0164)         ŧ (\u+0167) --> Ŧ (\u+0166) 
//    ũ (\u+0169) --> Ũ (\u+0168)         ū (\u+016B) --> Ū (\u+016A) 
//    ŭ (\u+016D) --> Ŭ (\u+016C)         ů (\u+016F) --> Ů (\u+016E) 
//    ű (\u+0171) --> Ű (\u+0170)         ų (\u+0173) --> Ų (\u+0172) 
//    ŵ (\u+0175) --> Ŵ (\u+0174)         ŷ (\u+0177) --> Ŷ (\u+0176) 
//    ź (\u+017A) --> Ź (\u+0179)         ż (\u+017C) --> Ż (\u+017B) 
//    ž (\u+017E) --> Ž (\u+017D)

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Date

History

Reason

May 2010

Replaced the example.

Customer feedback.

October 2008

Added a note that the method returns a new String object.

Customer feedback.

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