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String.Compare Method (String, String)

Compares two specified String objects.

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

'Declaration
Public Shared Function Compare ( _
	strA As String, _
	strB As String _
) As Integer
'Usage
Dim strA As String
Dim strB As String
Dim returnValue As Integer

returnValue = String.Compare(strA, strB)
public static int Compare (
	String strA, 
	String strB
)
public static function Compare (
	strA : String, 
	strB : String
) : int
Not applicable.

Parameters

strA

The first String.

strB

The second String.

Return Value

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

Value

Condition

Less than zero

strA is less than strB.

Zero

strA equals strB.

Greater than zero

strA is greater than strB.

The comparison uses the current culture 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 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

In the following code example, the ReverseStringComparer class demonstrates how you can evaluate two strings with the Compare method.

Imports System
Imports System.Text
Imports System.Collections



Public Class SamplesArrayList
    
    
    Public Shared Sub Main()
        Dim myAL As New ArrayList()
        ' Creates and initializes a new ArrayList.
        myAL.Add("Eric")
        myAL.Add("Mark")
        myAL.Add("Lance")
        myAL.Add("Rob")
        myAL.Add("Kris")
        myAL.Add("Brad")
        myAL.Add("Kit")
        myAL.Add("Bradley")
        myAL.Add("Keith")
        myAL.Add("Susan")
        
        ' Displays the properties and values of	the	ArrayList.
        Console.WriteLine("Count: {0}", myAL.Count)
        PrintValues("Unsorted", myAL)
        myAL.Sort()
        PrintValues("Sorted", myAL)
        Dim comp as New ReverseStringComparer
        myAL.Sort(comp)
        PrintValues("Reverse", myAL)

        Dim names As String() = CType(myAL.ToArray(GetType(String)), String())
    End Sub 'Main
   
   
    
    Public Shared Sub PrintValues(title As String, myList As IEnumerable)
        Console.Write("{0,10}: ", title)
        Dim sb As New StringBuilder()
        Dim s As String
        For Each s In  myList
            sb.AppendFormat("{0}, ", s)
        Next s
        sb.Remove(sb.Length - 2, 2)
        Console.WriteLine(sb)
    End Sub 'PrintValues
End Class 'SamplesArrayList

Public Class ReverseStringComparer 
  Implements IComparer
    
     Function Compare(x As Object, y As Object) As Integer implements IComparer.Compare
        Dim s1 As String = CStr (x)
        Dim s2 As String = CStr (y)
        
        'negate the return value to get the reverse order
        Return - [String].Compare(s1, s2)
    
    End Function 'Compare
End Class 'ReverseStringComparer


import System.*;
import System.Text.*;
import System.Collections.*;

public class SamplesArrayList
{
    public static void main(String[] args)
    {
        // Creates and initializes a new ArrayList.
        ArrayList myAL = new ArrayList();

        myAL.Add("Eric");
        myAL.Add("Mark");
        myAL.Add("Lance");
        myAL.Add("Rob");
        myAL.Add("Kris");
        myAL.Add("Brad");
        myAL.Add("Kit");
        myAL.Add("Bradley");
        myAL.Add("Keith");
        myAL.Add("Susan");

        // Displays the properties and values of the ArrayList.
        Console.WriteLine("Count: {0}", (Int32)myAL.get_Count());

        PrintValues("Unsorted", myAL);

        myAL.Sort();
        PrintValues("Sorted", myAL);

        myAL.Sort(new ReverseStringComparer());
        PrintValues("Reverse", myAL);

        String names[] = (String[])(myAL.ToArray(String.class.ToType()));
    } //main
    
    public static void PrintValues(String title, IEnumerable myList)
    {
        Console.Write("{0,10}: ", title);
        StringBuilder sb = new StringBuilder();
        IEnumerator objEnum = myList.GetEnumerator();
        while (objEnum.MoveNext()) {
            String s = System.Convert.ToString(objEnum.get_Current());
            sb.AppendFormat("{0}, ", s);
        }

        sb.Remove(sb.get_Length() - 2, 2);
        Console.WriteLine(sb);
    } //PrintValues
} //SamplesArrayList
 

public class ReverseStringComparer implements IComparer
{
    public int Compare(Object x, Object y)
    {
        String s1 = System.Convert.ToString(x);
        String s2 = System.Convert.ToString(y);

        //negate the return value to get the reverse order
        return -String.Compare(s1, s2);
    } //Compare 
} //ReverseStringComparer

import System;
import System.Text;
import System.Collections;

public class SamplesArrayList  {

	public static function Main() : void {
		// Creates and initializes a new ArrayList.
		var myAL : ArrayList = new ArrayList();
		myAL.Add("Eric");
		myAL.Add("Mark");
		myAL.Add("Lance");
		myAL.Add("Rob");
		myAL.Add("Kris");
		myAL.Add("Brad");
		myAL.Add("Kit");
		myAL.Add("Bradley");
		myAL.Add("Keith");
		myAL.Add("Susan");
	
		// Displays the properties and values of	the	ArrayList.
		Console.WriteLine( "Count: {0}", myAL.Count );
		
		PrintValues ("Unsorted", myAL );
		myAL.Sort();
		PrintValues("Sorted", myAL );
		myAL.Sort(new ReverseStringComparer() );
		PrintValues ("Reverse" , myAL );


		var names : String [] = (String[])(myAL.ToArray (System.String));


	}
	public static function PrintValues(title : String, myList: IEnumerable ) : void {
		Console.Write ("{0,10}: ", title);
		var sb : StringBuilder = new StringBuilder();
		for (var s : String in myList) {
			sb.AppendFormat( "{0}, ", s);
		}
		sb.Remove (sb.Length-2,2);
		Console.WriteLine(sb);
	}
}
public class ReverseStringComparer implements IComparer {
   public function Compare (x, y) : int  {
	   //negate the return value to get the reverse order
	   return - String.Compare (String(x), String(y));
   }
}
SamplesArrayList.Main();

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
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