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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.

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

public static int Compare (
	string strA,
	string strB,
	bool ignoreCase,
	CultureInfo culture
)
public static int Compare (
	String strA, 
	String strB, 
	boolean ignoreCase, 
	CultureInfo culture
)
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

Condition

Less than zero

strA is less than strB.

Zero

strA equals strB.

Greater than zero

strA is greater than strB.

Exception typeCondition

ArgumentNullException

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

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 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".

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

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

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

The following code 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'.

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
*/

import System.*;
import System.Globalization.*;

class Sample
{
    public static void main(String[] args)
    {
        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);
    } //main

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

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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