CompareInfo.IsPrefix Method (String, String, CompareOptions)

Determines whether the specified source string starts with the specified prefix using the specified CompareOptions value.

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

[SecuritySafeCriticalAttribute]
public virtual bool IsPrefix(
	string source,
	string prefix,
	CompareOptions options
)

Parameters

source
Type: System.String
The string to search in.
prefix
Type: System.String
The string to compare with the beginning of source.
options
Type: System.Globalization.CompareOptions
The CompareOptions value that defines how source and prefix should be compared. options is either the value Ordinal used by itself, or the bitwise combination of one or more of the following values: IgnoreCase, IgnoreSymbols, IgnoreNonSpace, IgnoreWidth, and IgnoreKanaType.

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.

ExceptionCondition
ArgumentNullException

source is null.

-or-

prefix is null.

ArgumentException

options contains an invalid CompareOptions value.

Every string starts and ends with an empty substring (""); therefore, if prefix is an empty string, this method returns true.

The CompareOptions.StringSort value is not valid for this method.

The following example determines whether a string is the prefix or suffix of another string using CompareOptions.


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;

      outputBlock.Text += String.Format("IsSuffix \"{0}\", \"{1}\"", myStr1, myXfix) + "\n";
      outputBlock.Text += String.Format("   With no CompareOptions            : {0}", myComp.IsSuffix(myStr1, myXfix)) + "\n";
      outputBlock.Text += String.Format("   With None                         : {0}", myComp.IsSuffix(myStr1, myXfix, CompareOptions.None)) + "\n";
      outputBlock.Text += String.Format("   With Ordinal                      : {0}", myComp.IsSuffix(myStr1, myXfix, CompareOptions.Ordinal)) + "\n";
      outputBlock.Text += String.Format("   With IgnoreCase                   : {0}", myComp.IsSuffix(myStr1, myXfix, CompareOptions.IgnoreCase)) + "\n";

      outputBlock.Text += String.Format("IsPrefix \"{0}\", \"{1}\"", myStr2, myXfix) + "\n";
      outputBlock.Text += String.Format("   With no CompareOptions            : {0}", myComp.IsPrefix(myStr2, myXfix)) + "\n";
      outputBlock.Text += String.Format("   With None                         : {0}", myComp.IsPrefix(myStr2, myXfix, CompareOptions.None)) + "\n";
      outputBlock.Text += String.Format("   With Ordinal                      : {0}", myComp.IsPrefix(myStr2, myXfix, CompareOptions.Ordinal)) + "\n";
      outputBlock.Text += String.Format("   With IgnoreCase                   : {0}", myComp.IsPrefix(myStr2, myXfix, CompareOptions.IgnoreCase)) + "\n";

   }

}


/*
This code produces the following output.

IsSuffix "calle", "LLE"
   With no CompareOptions            : False
   With None                         : False
   With Ordinal                      : False
   With IgnoreCase                   : True
IsPrefix "llegar", "LLE"
   With no CompareOptions            : False
   With None                         : False
   With Ordinal                      : False
   With IgnoreCase                   : True

*/


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

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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