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String.Replace Method (String, String)

Updated: March 2009

Returns a new string in which all occurrences of a specified string in this instance 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 equivalent to this instance but with all instances of oldValue 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 ReplaceTest {
    public static void Main() {

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

        Console.WriteLine("The original string is:{0}'{1}'{0}", Environment.NewLine, errString);

        // Correct the spelling of "document".

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

        Console.WriteLine("After correcting the string, the result is:{0}'{1}'",
                Environment.NewLine, correctString);
// 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' 

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




March 2009

Modified the member description.

Customer feedback.

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