Compares two specified String objects, ignoring or honoring their case, and returns an integer that indicates their relationship to one another in the sort order.
(in mscorlib.dll)
Visual Basic (Declaration)
Public Shared Function Compare ( _
strA As String, _
strB As String, _
ignoreCase As Boolean _
) As Integer
Dim strA As String
Dim strB As String
Dim ignoreCase As Boolean
Dim returnValue As Integer
returnValue = String.Compare(strA, _
strB, ignoreCase)
public static int Compare(
string strA,
string strB,
bool ignoreCase
)
public:
static int Compare(
String^ strA,
String^ strB,
bool ignoreCase
)
public static function Compare(
strA : String,
strB : String,
ignoreCase : boolean
) : int
Return Value
Type:
System..::.Int32A 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 nullNothingnullptra 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 bool IsFileURI(String path)
{
return (String.Compare(path, 0, "file:", 0, 5, true) == 0);
}
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:
static bool IsFileURI(String path)
{
return (String.Compare(path, 0, "file:", 0, 5, StringComparison.OrdinalIgnoreCase) == 0);
}
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
The following example demonstrates how this Compare method is equivalent to using ToUpper or ToLower when comparing strings.
unsafe
{
// Null terminated ASCII characters in an sbyte array
String szAsciiUpper = null;
sbyte[] sbArr1 = new sbyte[] { 0x41, 0x42, 0x43, 0x00 };
// Instruct the Garbage Collector not to move the memory
fixed(sbyte* pAsciiUpper = sbArr1)
{
szAsciiUpper = new String(pAsciiUpper);
}
String szAsciiLower = null;
sbyte[] sbArr2 = { 0x61, 0x62, 0x63, 0x00 };
// Instruct the Garbage Collector not to move the memory
fixed(sbyte* pAsciiLower = sbArr2)
{
szAsciiLower = new String(pAsciiLower, 0, sbArr2.Length);
}
// Prints "ABC abc"
Console.WriteLine(szAsciiUpper + " " + szAsciiLower);
// Compare Strings - the result is true
Console.WriteLine("The Strings are equal when capitalized ? " +
(String.Compare(szAsciiUpper.ToUpper(), szAsciiLower.ToUpper())==0?"true":"false") );
// This is the effective equivalent of another Compare method, which ignores case
Console.WriteLine("The Strings are equal when capitalized ? " +
(String.Compare(szAsciiUpper, szAsciiLower, true)==0?"true":"false") );
}
// Null terminated ASCII characters in a simple char array
char charArray3[4] = {0x41,0x42,0x43,0x00};
char * pstr3 = &charArray3[ 0 ];
String^ szAsciiUpper = gcnew String( pstr3 );
char charArray4[4] = {0x61,0x62,0x63,0x00};
char * pstr4 = &charArray4[ 0 ];
String^ szAsciiLower = gcnew String( pstr4,0,sizeof(charArray4) );
// Prints "ABC abc"
Console::WriteLine( String::Concat( szAsciiUpper, " ", szAsciiLower ) );
// Compare Strings - the result is true
Console::WriteLine( String::Concat( "The Strings are equal when capitalized ? ", (0 == String::Compare( szAsciiUpper->ToUpper(), szAsciiLower->ToUpper() ) ? (String^)"TRUE" : "FALSE") ) );
// This is the effective equivalent of another Compare method, which ignores case
Console::WriteLine( String::Concat( "The Strings are equal when capitalized ? ", (0 == String::Compare( szAsciiUpper, szAsciiLower, true ) ? (String^)"TRUE" : "FALSE") ) );
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
.NET Framework
Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
.NET Compact Framework
Supported in: 3.5, 2.0, 1.0
XNA Framework
Supported in: 3.0, 2.0, 1.0
Reference