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String.StartsWith Method (String)

Determines whether the beginning of this instance matches the specified string.

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

public bool StartsWith(
	string value
)

Parameters

value
Type: System.String
The string to compare.

Return Value

Type: System.Boolean
true if value matches the beginning of this string; otherwise, false.

ExceptionCondition
ArgumentNullException

value is null.

This method compares value to the substring at the beginning of this instance that is the same length as value, and returns an indication whether they are equal. To be equal, value must be an empty string (String.Empty), a reference to this same instance, or match the beginning of this instance.

This method performs a word (case-sensitive and culture-sensitive) comparison using the current culture.

Notes to Callers

Starting in Silverlight 4, the behavior of the String.StartsWith(String) method has changed. In Silverlight 4, it performs a case-sensitive and culture-sensitive comparison using the current culture to determine whether the current instance begins with value. This conforms to the behavior of the String.StartsWith(String) method in the full .NET Framework. In Silverlight 2 and Silverlight 3, String.StartsWith(String) performs an ordinal comparison using the current culture. If the common language runtime determines that a Silverlight-based application was compiled against Silverlight 2 or Silverlight 3, it performs an ordinal comparison; otherwise, it performs a culture-sensitive comparison.

The following code example demonstrates how you can use the StartsWith method.


using System;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {

      // process a string that contains html tags
      // this sample does not remove embedded tags (tags in the middle of a line)

      string[] strSource = { "<b>This is bold text</b>", "<H1>This is large Text</H1>",
                "<b><i><font color=green>This has multiple tags</font></i></b>",
                "<b>This has <i>embedded</i> tags.</b>",
                "<This line simply begins with a lesser than symbol, it should not be modified" };

      outputBlock.Text += "The following lists the items before the tags have been stripped:" + "\n";
      outputBlock.Text += "-----------------------------------------------------------------" + "\n";

      // print out the initial array of strings
      foreach (string s in strSource)
         outputBlock.Text += s + "\n";

      outputBlock.Text += "\n";

      outputBlock.Text += "The following lists the items after the tags have been stripped:" + "\n";
      outputBlock.Text += "----------------------------------------------------------------" + "\n";

      // print out the array of strings
      foreach (string s in strSource)
         outputBlock.Text += StripStartTags(s) + "\n";
   }

   private static string StripStartTags(string item)
   {

      // try to find a tag at the start of the line using StartsWith
      if (item.Trim().StartsWith("<"))
      {

         // now search for the closing tag...
         int lastLocation = item.IndexOf(">");

         // remove the identified section, if it is a valid region
         if (lastLocation >= 0)
            item = item.Substring(lastLocation + 1);
      }

      return item;
   }
}


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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