Windows apps
Collapse the table of content
Expand the table of content
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.

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


Compares two specified String objects, ignoring or honoring their case, and using culture-specific information to influence the comparison, and returns an integer that indicates their relative position in the sort order.

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

Public Shared Function Compare (
	strA As String,
	strB As String,
	ignoreCase As Boolean,
	culture As CultureInfo
) As Integer


Type: System.String

The first string to compare.

Type: System.String

The second string to compare.

Type: System.Boolean

true to ignore case during the comparison; otherwise, false.

Type: System.Globalization.CultureInfo

An object that supplies culture-specific comparison information.

Return Value

Type: System.Int32

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



Less than zero

strA precedes strB in the sort order.


strA occurs in the same position as strB in the sort order.

Greater than zero

strA follows strB in the sort order.

Exception Condition

culture is null.

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 null. 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 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
        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
        Return False
    End If
End Function

Notes to Callers:

Character sets include ignorable characters. The Compare(String, String, Boolean, CultureInfo) method does not consider such characters when it performs a culture-sensitive comparison. For example, if the following code is run on the .NET Framework 4 or later, a case-insensitive comparison of "animal" with "Ani-mal" (using a soft hyphen, or U+00AD) using the invariant culture indicates that the two strings are equivalent.

Imports System.Globalization

Module Example
   Public Sub Main()
      Dim s1 As String = "Ani" + ChrW(&h00AD) + "mal"
      Dim s2 As String = "animal"

      Console.WriteLine("Comparison of '{0}' and '{1}': {2}", 
                        s1, s2, String.Compare(s1, s2, True,
  End Sub
End Module
' The example displays the following output:
'       Comparison of 'ani-mal' and 'animal': 0

To recognize ignorable characters in a string comparison, call theCompare method and supply a value of either CompareOptions.Ordinal or CompareOptions.OrdinalIgnoreCase for the options parameter.

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".

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 = "<"
         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

.NET Framework
Available since 1.1
Return to top
© 2017 Microsoft