String Replace() Method in C#

In C#, the Replace() method is used to replace all occurrences of a specified substring or character in a string with another substring or character. This method is particularly useful for string manipulation tasks, such as formatting or cleaning up data.

Example : Using Replace() method to replace "World" with "Geeks" in a string.

Before Replacing: Hello, World
After Replacing: Hello, Geeks

Explanation: In the above example, we use a Replace() method of the String class to replace the World with Geeks.

Syntax

public string Replace(char oldChar, char newChar)
public string Replace(string oldValue, string newValue)

Parameters:

• oldChar: The character which is to be replaced.
• newChar: The new character will be replaced with the old character.
• oldValue: The old substring which is to be replaced.
• newValue: New substring that will replace with the old value.

Return Type:

• This method returns a new string (System.String) where all occurrences of the specified character or substring are replaced with the given value. The original string remains unchanged.

Exceptions:

• ArgumentNullException: If oldValue is null.
• ArgumentException: If oldValue is an empty string (" ").

Example 1: Using the Replace() method to replace all occurrences of a specified substring with a new substring.

Hello, Geeks

Explanation: In the above example, the Replace() method replaces "Geek" with "Geeks" in the original string and returns a new string.

Example 2: Using the Replace() method to replace the specified character from the string.

Modified String: Hella, Warld!

Explanation: In the above example, we use the Replace() method which replaces all occurrences of a specified character with a new character. As shown the character 'o' replaces with 'a'.

Example 3: Using the Replace() method in a Case-Sensitive Manner.

Hello, World!

Explanation: In the above example, the string value passed as "hello" (lowercase) is not found in the original string, so no replacement was done because the Replace() method is case-sensitive.

Example 4: Performing multiple replacement operations on the String (Replacement’s Chain) using the Replace() method.

Modified String: Hello, Geeks! Welcome to the Geeks of C Sharp!

Explanation: In the above example, the multiple replacement operation is performed using the Replace() method of string class the world "World" with "Geeks" and "C#" with "C Sharp" using method chaining.