.NET Framework Class Library
StringCompare Method (String, Int32, String, Int32, Int32)

Compares substrings of two specified String objects and returns an integer that indicates their relative position in the sort order.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)
Syntax
Public Shared Function Compare ( _
	strA As [%$TOPIC/x7tax739_en-us_VS_110_2_0_0_0_0%], _
	indexA As [%$TOPIC/x7tax739_en-us_VS_110_2_0_0_0_1%], _
	strB As [%$TOPIC/x7tax739_en-us_VS_110_2_0_0_0_2%], _
	indexB As [%$TOPIC/x7tax739_en-us_VS_110_2_0_0_0_3%], _
	length As [%$TOPIC/x7tax739_en-us_VS_110_2_0_0_0_4%] _
) As [%$TOPIC/x7tax739_en-us_VS_110_2_0_0_0_5%]
public static [%$TOPIC/x7tax739_en-us_VS_110_2_0_1_0_0%] Compare(
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_1_0_1%] strA,
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_1_0_2%] indexA,
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_1_0_3%] strB,
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_1_0_4%] indexB,
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_1_0_5%] length
)
public:
static [%$TOPIC/x7tax739_en-us_VS_110_2_0_2_0_0%] Compare(
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_2_0_1%]^ strA, 
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_2_0_2%] indexA, 
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_2_0_3%]^ strB, 
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_2_0_4%] indexB, 
	[%$TOPIC/x7tax739_en-us_VS_110_2_0_2_0_5%] length
)
static member Compare : 
        strA:[%$TOPIC/x7tax739_en-us_VS_110_2_0_3_0_0%] * 
        indexA:[%$TOPIC/x7tax739_en-us_VS_110_2_0_3_0_1%] * 
        strB:[%$TOPIC/x7tax739_en-us_VS_110_2_0_3_0_2%] * 
        indexB:[%$TOPIC/x7tax739_en-us_VS_110_2_0_3_0_3%] * 
        length:[%$TOPIC/x7tax739_en-us_VS_110_2_0_3_0_4%] -> [%$TOPIC/x7tax739_en-us_VS_110_2_0_3_0_5%]

Parameters

strA
Type: SystemString

The first string to use in the comparison.

indexA
Type: SystemInt32

The position of the substring within strA.

strB
Type: SystemString

The second string to use in the comparison.

indexB
Type: SystemInt32

The position of the substring within strB.

length
Type: SystemInt32

The maximum number of characters in the substrings to compare.

Return Value

Type: SystemInt32
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.

Exceptions
ExceptionCondition
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 , and length is greater than zero.

Remarks

The substrings to compare start in strA at indexA and in strB at indexB. Both indexA and indexB are zero-based; that is, the first character in strA and strB is at position zero. The length of the first substring is equal to the length of strA minus indexA plus one. The length of the second substring is equal to the length of strB minus indexB plus one.

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.GlobalizationCompareOptions.

Caution noteCaution

When comparing strings, you should call the Compare(String, Int32, String, Int32, Int32, StringComparison) method, which requires that you explicitly specify the type of string comparison that the method uses. For more information, see Best Practices for Using Strings in the .NET Framework.

One or both comparands can be . 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
static bool IsFileURI(String path)
{
    return (String.Compare(path, 0, "file:", 0, 5, true) == 0);
}
static bool 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:

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

Notes to Callers

Character sets include ignorable characters. The Compare(String, Int32, String, Int32, Int32) method does not consider these characters when it performs a linguistic or culture-sensitive comparison. To recognize ignorable characters in your comparison, call the Compare(String, Int32, String, Int32, Int32, StringComparison) method and supply a value of CompareOptionsOrdinal or CompareOptionsOrdinalIgnoreCase for the comparisonType parameter.

Examples

The following example compares two substrings.

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

Class Sample
   Public Shared Sub Main()
      '                       0123456 
      Dim str1 As [String] = "machine" 
      Dim str2 As [String] = "device" 
      Dim str As [String]
      Dim result As Integer

      Console.WriteLine()
      Console.WriteLine("str1 = '{0}', str2 = '{1}'", str1, str2)
      result = [String].Compare(str1, 2, str2, 0, 2)
      str = IIf(result < 0, "less than", IIf(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)
   End Sub 'Main
End Class 'Sample
' 
'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) 
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) 
using namespace System;
int 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) ? (String^)"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'.
*/
Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
Platforms

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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