Export (0) Print
Expand All

String.Compare Method (String, Int32, String, Int32, Int32, Boolean, CultureInfo)

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

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

'Declaration
Public Shared Function Compare ( _
	strA As String, _
	indexA As Integer, _
	strB As String, _
	indexB As Integer, _
	length As Integer, _
	ignoreCase As Boolean, _
	culture As CultureInfo _
) As Integer
'Usage
Dim strA As String
Dim indexA As Integer
Dim strB As String
Dim indexB As Integer
Dim length As Integer
Dim ignoreCase As Boolean
Dim culture As CultureInfo
Dim returnValue As Integer

returnValue = String.Compare(strA, indexA, strB, indexB, length, ignoreCase, culture)
public static int Compare (
	String strA, 
	int indexA, 
	String strB, 
	int indexB, 
	int length, 
	boolean ignoreCase, 
	CultureInfo culture
)
public static function Compare (
	strA : String, 
	indexA : int, 
	strB : String, 
	indexB : int, 
	length : int, 
	ignoreCase : boolean, 
	culture : CultureInfo
) : int
Not applicable.

Parameters

strA

The first String.

indexA

The position of the substring within strA.

strB

The second String.

indexB

The position of the substring within the strB.

length

The maximum number of characters in the substrings to compare.

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

An integer indicating the lexical relationship between the two comparands.

Value

Condition

Less than zero

The substring in strA is less than the substring in strB.

Zero

The substrings are equal, or length is zero.

Greater than zero

The substring in strA is greater than the substring in strB.

Exception typeCondition

ArgumentOutOfRangeException

indexA is greater than strA.Length.

-or-

indexB is greater than strB.Length.

-or-

indexA, indexB, or length is negative.

-or-

Either indexA or indexB is a null reference (Nothing in Visual Basic), and length is greater than zero.

ArgumentNullException

culture is a null reference (Nothing in Visual Basic).

The substrings to compare start at strA plus indexA, and strB plus indexB. The length of the first substring is the length of strA minus indexA, and the length of the second substring is the length of strB minus indexB.

The number of characters to compare is the lesser of the lengths of the two substrings, and length. The indexA, indexB, and length parameters must be nonnegative.

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 substrings have been compared. However, if the two strings compare equal to the end of one string, and the 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".

 Shared Function IsFileURI(ByVal path As String) As Boolean
    If String.Compare(path, 0, "file:", 0, 5, True) = 0 Then
       Return True
    Else
       Return False
    End If
 End Function

Compare the path name to "file" using an ordinal comparison. The correct code to do this is as follows:

Shared Function IsFileURI(ByVal path As String) As Boolean
    If String.Compare(path, 0, "file:", 0, 5, StringComparison.OrdinalIgnoreCase) = 0 Then
       Return True
    Else
       Return False
    End If
 End Function

The following code example compares two substrings using different cultures and ignoring the case of the substrings. The choice of culture affects how the letter 'I' is compared.

' Sample for String.Compare(String, Int32, String, Int32, Int32, Boolean, CultureInfo)
Imports System
Imports System.Globalization
Imports Microsoft.VisualBasic

Class Sample
   
   Public Shared Sub Main()
      '                       0123456
      Dim str1 As [String] = "MACHINE"
      Dim str2 As [String] = "machine"
      Dim str As [String]
      Dim result As Integer
      
      Console.WriteLine()
      Console.WriteLine("str1 = '{0}', str2 = '{1}'", str1, str2)
      Console.WriteLine("Ignore case, Turkish culture:")
      result = [String].Compare(str1, 4, str2, 4, 2, True, New CultureInfo("tr-TR"))
      str = IIf(result < 0, "less than", IIf(result > 0, "greater than", "equal to"))
      Console.Write("Substring '{0}' in '{1}' is ", str1.Substring(4, 2), str1)
      Console.Write("{0} ", str)
      Console.WriteLine("substring '{0}' in '{1}'.", str2.Substring(4, 2), str2)
      
      Console.WriteLine()
      Console.WriteLine("Ignore case, invariant culture:")
      result = [String].Compare(str1, 4, str2, 4, 2, True, CultureInfo.InvariantCulture)
      str = IIf(result < 0, "less than", IIf(result > 0, "greater than", "equal to"))
      Console.Write("Substring '{0}' in '{1}' is ", str1.Substring(4, 2), str1)
      Console.Write("{0} ", str)
      Console.WriteLine("substring '{0}' in '{1}'.", str2.Substring(4, 2), str2)
   End Sub 'Main
End Class 'Sample
'
'This example produces the following results:
'
'str1 = 'MACHINE', str2 = 'machine'
'Ignore case, Turkish culture:
'Substring 'IN' in 'MACHINE' is less than substring 'in' in 'machine'.
'
'Ignore case, invariant culture:
'Substring 'IN' in 'MACHINE' is equal to substring 'in' in 'machine'.
'

// Sample for String.Compare(String, Int32, String, Int32, Int32, Boolean, 
// CultureInfo)
import System.*;
import System.Globalization.*;

class Sample
{
    public static void main(String[] args)
    {
        //                 0123456
        String str1 = "MACHINE";
        String str2 = "machine";
        String str;
        int result;

        Console.WriteLine();
        Console.WriteLine("str1 = '{0}', str2 = '{1}'", str1, str2);
        Console.WriteLine("Ignore case, Turkish culture:");
        result = String.Compare(str1, 4, str2, 4, 2, true, 
            new CultureInfo("tr-TR"));
        str = result < 0 ? "less than" : (result > 0) ? "greater than" : 
            "equal to";
        Console.Write("Substring '{0}' in '{1}' is ", str1.Substring(4, 2), 
            str1);
        Console.Write("{0} ", str);
        Console.WriteLine("substring '{0}' in '{1}'.", str2.Substring(4, 2), 
            str2);
        Console.WriteLine();

        Console.WriteLine("Ignore case, invariant culture:");
        result = String.Compare(str1, 4, str2, 4, 2, true, 
            CultureInfo.get_InvariantCulture());
        str = result < 0 ? "less than" : (result > 0) ? "greater than" : 
            "equal to";
        Console.Write("Substring '{0}' in '{1}' is ", str1.Substring(4, 2), 
            str1);
        Console.Write("{0} ", str);
        Console.WriteLine("substring '{0}' in '{1}'.", str2.Substring(4, 2), 
            str2);
    } //main
} //Sample
/*
This example produces the following results:

str1 = 'MACHINE', str2 = 'machine'
Ignore case, Turkish culture:
Substring 'IN' in 'MACHINE' is less than substring 'in' in 'machine'.

Ignore case, invariant culture:
Substring 'IN' in 'MACHINE' is equal to substring 'in' in 'machine'.
*/

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

Community Additions

ADD
Show:
© 2014 Microsoft