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String.Compare Method (String, String, Boolean, CultureInfo)

.NET Framework 1.1

Compares two specified String objects, ignoring or honoring their case, and using culture-specific information to influence the comparison.

[Visual Basic]
Overloads Public Shared Function Compare( _
   ByVal strA As String, _
   ByVal strB As String, _
   ByVal ignoreCase As Boolean, _
   ByVal culture As CultureInfo _
) As Integer
[C#]
public static int Compare(
 string strA,
 string strB,
 bool ignoreCase,
 CultureInfo culture
);
[C++]
public: static int Compare(
 String* strA,
 String* strB,
 bool ignoreCase,
 CultureInfo* culture
);
[JScript]
public static function Compare(
   strA : String,
 strB : String,
 ignoreCase : Boolean,
 culture : CultureInfo
) : int;

Parameters

strA
The first String.
strB
The second String.
ignoreCase
A Boolean indicating a case-sensitive or insensitive comparison. (true indicates a case-insensitive comparison.)
culture
A CultureInfo object that supplies culture-specific comparison information.

Return Value

A 32-bit signed integer indicating the lexical relationship between the two comparands.

Value Meaning
Less than zero strA is less than strB.
Zero strA equals strB.
Greater than zero strA is greater than strB.

Exceptions

Exception Type Condition
ArgumentNullException culture is a null reference (Nothing in Visual Basic).

Remarks

The comparison uses the culture parameter to obtain culture-specific information such as casing rules and the alphabetic order of individual characters. For example, a culture could specify that certain combinations of characters be treated as a single character, or uppercase and lowercase characters be compared in a particular way, or that the sorting order of a character depends on the characters that precede or follow it.

The comparison is performed using word sort rules. For more information about word, string, and ordinal sorts, see System.Globalization.CompareOptions.

One or both comparands can be a null reference (Nothing in Visual Basic). By definition, any string, including the empty string (""), compares greater than a null reference; and two null references compare equal to each other.

The comparison terminates when an inequality is discovered or both strings have been compared. However, if the two strings compare equal to the end of one string, and other string has characters remaining, then the string with remaining characters is considered greater. The return value is the result of the last comparison performed.

Unexpected results can occur when comparisons are affected by culture-specific casing rules. For example, in Turkish, the following example yields the wrong results because the file system in Turkish does not use linguistic casing rules for the letter 'i' in "file".

static String IsFileURI(String path) { 
   return (String.Compare(path, 0, "file:", 0, 5, true)== 0); }

The path name needs to be compared in an invariant manner. The correct code to do this is as follows.

static String IsFileURI(String path) { 
   return (String.Compare(path, 0, "file:", 0, 5, true, CultureInfo.InvariantCulture)== 0); }

Example

[Visual Basic, C#, C++] The following example demonstrates how culture can affect a comparison. In Czech - Czech Republic culture, 'ch' is a single character that is greater than 'd'. However, in English - United States culture, "ch" consists of two characters, and 'c' is less than 'd'.

[Visual Basic] 
Imports System
Imports System.Globalization
 _

Class Sample
   Public Shared Sub Main()
      Dim str1 As [String] = "change"
      Dim str2 As [String] = "dollar"
      Dim relation As [String] = Nothing
      
      relation = symbol([String].Compare(str1, str2, False, New CultureInfo("en-US")))
      Console.WriteLine("For en-US: {0} {1} {2}", str1, relation, str2)
      
      relation = symbol([String].Compare(str1, str2, False, New CultureInfo("cs-CZ")))
      Console.WriteLine("For cs-CZ: {0} {1} {2}", str1, relation, str2)
   End Sub 'Main
   
   Private Shared Function symbol(r As Integer) As [String]
      Dim s As [String] = "="
      If r < 0 Then
         s = "<"
      Else
         If r > 0 Then
            s = ">"
         End If
      End If
      Return s
   End Function 'symbol
End Class 'Sample
'
'This example produces the following results.
'For en-US: change < dollar
'For cs-CZ: change > dollar
'

[C#] 
using System;
using System.Globalization;

class Sample {
    public static void Main() {
    String str1 = "change";
    String str2 = "dollar";
    String relation = null;

    relation = symbol( String.Compare(str1, str2, false, new CultureInfo("en-US")) );
    Console.WriteLine("For en-US: {0} {1} {2}", str1, relation, str2);

    relation = symbol( String.Compare(str1, str2, false, new CultureInfo("cs-CZ")) );
    Console.WriteLine("For cs-CZ: {0} {1} {2}", str1, relation, str2);
    }

    private static String symbol(int r) {
    String s = "=";
    if      (r < 0) s = "<";
    else if (r > 0) s = ">";
    return s;
    }
}
/*
This example produces the following results.
For en-US: change < dollar
For cs-CZ: change > dollar
*/

[C++] 
#using <mscorlib.dll>
using namespace System;
using namespace System::Globalization;

String * symbol(int r)
{
   String * s = S"=";
   if (r < 0) 
      s = S"<";
   else if (r > 0) 
      s = S">";
   return s;
}

int main()
{
   String * str1 = S"change";
   String * str2 = S"dollar";
   String* relation = 0;

   relation = symbol(String::Compare(str1, str2, false, new CultureInfo(S"en-US")));
   Console::WriteLine(S"For en-US: {0} {1} {2}", str1, relation, str2);

   relation = symbol(String::Compare(str1, str2, false, new CultureInfo(S"cs-CZ")));
   Console::WriteLine(S"For cs-CZ: {0} {1} {2}", str1, relation, str2);
}
/*
This example produces the following results.
For en-US: change < dollar
For cs-CZ: change > dollar
*/

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

See Also

String Class | String Members | System Namespace | String.Compare Overload List | Int32 | CompareOrdinal | CompareTo | IsPrefix | Boolean

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