CompareInfo.IsPrefix Method (String, String)
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Determines whether the specified source string starts with the specified prefix.
Namespace: System.Globalization
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Overridable Function IsPrefix ( _
source As String, _
prefix As String _
) As Boolean
public virtual bool IsPrefix(
string source,
string prefix
)
Parameters
- source
Type: System.String
The string to search in.
- prefix
Type: System.String
The string to compare with the beginning of source.
Return Value
Type: System.Boolean
true if the length of prefix is less than or equal to the length of source and source starts with prefix; otherwise, false.
Exceptions
| Exception | Condition |
|---|---|
| ArgumentNullException | source is nulla null reference (Nothing in Visual Basic). -or- prefix is nulla null reference (Nothing in Visual Basic). |
Remarks
Every string starts and ends with an empty substring (""); therefore, if prefix is an empty string, this method returns true.
Examples
The following example determines whether a string is the prefix or suffix of another string.
Imports System.Globalization
Public Class Example
Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
' Defines the strings to compare.
Dim myStr1 As [String] = "calle"
Dim myStr2 As [String] = "llegar"
Dim myXfix As [String] = "lle"
' Uses the CompareInfo property of the InvariantCulture.
Dim myComp As CompareInfo = CultureInfo.InvariantCulture.CompareInfo
' Determines whether myXfix is a prefix of "calle" and "llegar".
outputBlock.Text += String.Format("IsPrefix( {0}, {1} ) : {2}", myStr1, myXfix, myComp.IsPrefix(myStr1, myXfix)) & vbCrLf
outputBlock.Text += String.Format("IsPrefix( {0}, {1} ) : {2}", myStr2, myXfix, myComp.IsPrefix(myStr2, myXfix)) & vbCrLf
' Determines whether myXfix is a suffix of "calle" and "llegar".
outputBlock.Text += String.Format("IsSuffix( {0}, {1} ) : {2}", myStr1, myXfix, myComp.IsSuffix(myStr1, myXfix)) & vbCrLf
outputBlock.Text += String.Format("IsSuffix( {0}, {1} ) : {2}", myStr2, myXfix, myComp.IsSuffix(myStr2, myXfix)) & vbCrLf
End Sub 'Main
End Class 'SamplesCompareInfo
'This code produces the following output.
'
'IsPrefix( calle, lle ) : False
'IsPrefix( llegar, lle ) : True
'IsSuffix( calle, lle ) : True
'IsSuffix( llegar, lle ) : False
using System;
using System.Globalization;
public class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
// Defines the strings to compare.
String myStr1 = "calle";
String myStr2 = "llegar";
String myXfix = "lle";
// Uses the CompareInfo property of the InvariantCulture.
CompareInfo myComp = CultureInfo.InvariantCulture.CompareInfo;
// Determines whether myXfix is a prefix of "calle" and "llegar".
outputBlock.Text += String.Format("IsPrefix( {0}, {1} ) : {2}", myStr1, myXfix, myComp.IsPrefix(myStr1, myXfix)) + "\n";
outputBlock.Text += String.Format("IsPrefix( {0}, {1} ) : {2}", myStr2, myXfix, myComp.IsPrefix(myStr2, myXfix)) + "\n";
// Determines whether myXfix is a suffix of "calle" and "llegar".
outputBlock.Text += String.Format("IsSuffix( {0}, {1} ) : {2}", myStr1, myXfix, myComp.IsSuffix(myStr1, myXfix)) + "\n";
outputBlock.Text += String.Format("IsSuffix( {0}, {1} ) : {2}", myStr2, myXfix, myComp.IsSuffix(myStr2, myXfix)) + "\n";
}
}
/*
This code produces the following output.
IsPrefix( calle, lle ) : False
IsPrefix( llegar, lle ) : True
IsSuffix( calle, lle ) : True
IsSuffix( llegar, lle ) : False
*/
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.