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

Compares substrings of two specified String objects.

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

public static int Compare (
	string strA,
	int indexA,
	string strB,
	int indexB,
	int length
)
public static int Compare (
	String strA, 
	int indexA, 
	String strB, 
	int indexB, 
	int length
)
public static function Compare (
	strA : String, 
	indexA : int, 
	strB : String, 
	indexB : int, 
	length : int
) : int

Parameters

strA

The first String.

indexA

The position of the substring within strA.

strB

The second String.

indexB

The position of the substring within strB.

length

The maximum number of characters in the substrings to compare.

Return Value

A 32-bit signed 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.

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 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 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".

 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 compares two substrings.

// Sample for String.Compare(String, Int32, String, Int32, Int32)
using System;

class Sample {
    public static void Main() {
//                 0123456
    String str1 = "machine";
    String str2 = "device";
    String str;
    int result;

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

str1 = 'machine', str2 = 'device'
Substring 'ch' in 'machine' is less than substring 'de' in 'device'.
*/

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

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

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

str1 = 'machine', str2 = 'device'
Substring 'ch' in 'machine' is less than substring 'de' in 'device'.
*/

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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