There are several different situations where you will want or need to know how to replace a string in C#. For example, if you need to change the word “blue” with “red” somewhere in a document, you might use a replacement operation to do so. Replacing strings in C# is straightforward once you understand the syntax and sequence of operations.
Accordingly, in C#, you can replace a string with another string just like in other programming languages such as Java and C++. In this tutorial, we’ll be discussing how you can replace a string in C# with different methods.
- Using the
string.Replace() Method - Using the
StringBuilder.Replace()Method - Using the
Regex.Replace()Method
Each of these approaches comes with its advantages and disadvantages. Let’s take a look at them now with the help of examples.
Using the String.Replace() Method
The most straightforward way to replace a string in C# is to use the built-in method String.Replace()..
Syntax
string.replace (Oldvalue, Newvalue)
Parameters
With this method, you pass in the following parameters:
- Oldvalue: The string that you want to replace. This can be a literal string or a variable holding a string.
- Newvalue: The string that you want to replace it with. This can be a literal string or a variable holding a string.
Return Value
This method returns the String object after replacing the Oldvalue with Newvalue.
Example
The following example shows the String.Replace() method in C#.
using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string str = "New C sharp Tutorial";
// replaces "New" with "Best"
string result = str.Replace("New", "Best");
Console.WriteLine(result);
Console.ReadLine();
}
}
When the above code is compiled and executed, it produces the following result:
Output
Best C sharp Tutorial
Using the StringBuilder.Replace() Method
The StringBuilder.Replace() method in C# is used to replace the specified old value with the new value in the current StringBuilder object. This method returns a new StringBuilder object that represents the modified string.
Syntax
StringBuilder.Replace(remValue, repValue)
Parameters
- remValue: It is the string to be replaced.
- repValue: It is the string that will replace the remValue.
Return Value
This method returns the StringBuilder object after replacing the remValue with repValue.
Example
The following example shows the StringBuilder.Replace() method in C#.
using System;
using System.Text;
class Example
{
public static void Main()
{
StringBuilder str = new StringBuilder("Hello this is First C sharp Tutorial");
// Replace 'First' with 'Best'
str.Replace("First", "Best");
// Display the string.
Console.WriteLine(str);
}
}
When the above code is compiled and executed, it produces the following result:
Hello this is Best C sharp Tutorial
Using the Regex.Replace() Methods
The Regex.Replace() method in C# is used to replace the characters in a specified input string that matches a specified regular expression pattern with a specified replacement string. The input string can be any character sequence, and the replacement string can contain any characters. Optionally, Regex.Replace() can take a regular expression pattern as its first argument.
Syntax
Regex.Replace(input, replacementPattern, replacementText);
Parameters
- input: It is the string to be replaced,
- replacementPattern: It is the regular expression pattern to match
- replacementText: Is the replacement text.
The fifth and sixth parameters are also optional and specify the regular expression options and the time-out interval for the match respectively.
Example
The following example illustrates the use of the Regex.Replace() method to replace all occurrences of the word “New” with the word “Best”.
using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string input = "New C sharp Tutorial";
string pattern = "New";
string replacement = "Best";
Console.WriteLine(Regex.Replace(input, pattern, replacement));
}
}
When the above code is compiled and executed, it produces the following result:
Output
Best C sharp Tutorial
Summery
The most straightforward way to replace a string in C# is to use the built-in method String.Replace(). With this method, you pass in the following parameters: – The string that you want to replace – This can be a literal string or a variable holding a string. – The string that you want to replace it with – This can be a literal string or a variable holding a string. The target string that you want to search for – This can be a literal string or a variable holding a string. Replacement options – There are two different options you can use for this parameter: Moreover, you can also use string replacement functions or regular expressions to replace a string in C#. Depending on your needs, you may want to use one over the others.
