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String.Replace Method (String, String)

Returns a new string in which all occurrences of a specified string in the current string are replaced with another specified string.

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

public string Replace(
	string oldValue,
	string newValue


Type: System.String
A string to be replaced.
Type: System.String
A string to replace all occurrences of oldValue.

Return Value

Type: System.String
A string that is equivalent to the current string except that all instances of oldValue are replaced with newValue.


oldValue is null.


oldValue is the empty string ("").

If newValue is null, all occurrences of oldValue are removed.


This method does not modify the value of the current instance. Instead, it returns a new string in which all occurrences of oldValue are replaced by newValue.

This method performs an ordinal (case-sensitive and culture-insensitive) search to find oldValue.

The following example demonstrates how you can use the Replace method to correct a spelling error.

using System;

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

      string errString = "This docment uses 3 other docments to docment the docmentation";

      outputBlock.Text += String.Format("The original string is:{0}'{1}'{0}", "\n", errString) + "\n";

      // Correct the spelling of "document".

      string correctString = errString.Replace("docment", "document");

      outputBlock.Text += String.Format("After correcting the string, the result is:{0}'{1}'",
              "\n", correctString) + "\n";
// This code example produces the following output:
// The original string is:
// 'This docment uses 3 other docments to docment the docmentation'
// After correcting the string, the result is:
// 'This document uses 3 other documents to document the documentation'


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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