Replace String in C#

Here are some examples on how to replace strings in C#:

Replace a String to other text with case insensitive in C#:

To replace a string with another string with case-insensitive matching, you can use the Replace method with StringComparison option:

string input = "Hello world!";
string replacement = "bye";
string result = input.Replace("HELLO", replacement, StringComparison.OrdinalIgnoreCase);

In this example, the string "Hello" is replaced with "bye" in the input string, regardless of the case.

Replace of a String in place using C#:

To replace a string in place, you can use the StringBuilder class:

StringBuilder sb = new StringBuilder("Hello world!");
sb.Replace("Hello", "Hi");
string result = sb.ToString();

In this example, the StringBuilder class is used to replace the string "Hello" with "Hi" in the sb object.

Replace the first searched instance of a String in C#:

To replace only the first occurrence of a string, you can use the Replace method with a limit parameter:

string input = "Hello world, Hello everyone!";
string replacement = "Hi";
string result = input.Replace("Hello", replacement, 1);

In this example, only the first occurrence of "Hello" is replaced with "Hi" in the input string.

Replace Line Breaks in a String to other text using C#:

To replace line breaks with other text, you can use the Replace method with the Environment.NewLine constant:

string input = "Hello" + Environment.NewLine + "world!";
string replacement = "<br/>";
string result = input.Replace(Environment.NewLine, replacement);

In this example, the Environment.NewLine constant is used to represent the line breaks in the input string, and they are replaced with the <br/> tag.

How to replace multiple line breaks with a single <br/> in C#:

To replace multiple line breaks with a single <br/> tag, you can use a regular expression:

string input = "Hello" + Environment.NewLine + Environment.NewLine + "world!";
string result = Regex.Replace(input, @"(\r\n|\r|\n)+", "<br/>");

In this example, the regular expression (\r\n|\r|\n)+ matches one or more occurrences of line breaks (\r\n, \r, or \n), and replaces them with a single <br/> tag.

How to replace 1 line break with 2 line breaks in C#:

To replace one line break with two line breaks, you can use the Replace method with a double line break string:

string input = "Hello" + Environment.NewLine + "world!";
string result = input.Replace(Environment.NewLine, Environment.NewLine + Environment.NewLine);

In this example, the Environment.NewLine constant is used to represent the line breaks in the input string, and each occurrence is replaced with two line breaks.

How to replace multiple spaces with a single space in C#:

To replace multiple spaces with a single space, you can use a regular expression:

string input = "Hello     world!";
string result = Regex.Replace(input, @"\s+", " ");

In this example, the regular expression \s+ matches one or more whitespace characters, and replaces them with a single space.

C# replace string example:

string input = "Replace this string";
string oldString = "this";
string newString = "that";
string result = input.Replace(oldString, newString);
// Result: "Replace that string"

Replace substring in C# string:

string input = "Replace this substring";
string oldSubstring = "this";
string newSubstring = "that";
string result = input.Replace(oldSubstring, newSubstring);
// Result: "Replace that substring"

Replacing characters in C# string:

string input = "Replace characters";
char charToReplace = 'e';
char replacementChar = '*';
string result = input.Replace(charToReplace, replacementChar);
// Result: "R*plac* charact*rs"

C# replace multiple occurrences in string:

string input = "Replace multiple multiple occurrences";
string target = "multiple";
string replacement = "single";
string result = input.Replace(target, replacement);
// Result: "Replace single single occurrences"

Case-insensitive string replacement in C#:

string input = "Replace case-insensitive";
string target = "CASE";
string replacement = "case";
string result = input.Replace(target, replacement, StringComparison.OrdinalIgnoreCase);
// Result: "Replace case-insensitive"

C# regex replace string:

using System.Text.RegularExpressions;

string input = "Replace using regex";
string pattern = "using";
string replacement = "with";
string result = Regex.Replace(input, pattern, replacement);
// Result: "Replace with regex"

Replace part of a string in C#:

string input = "Replace part of this string";
int startIndex = 12;
int length = 4;
string replacement = "portion";
string result = input.Remove(startIndex, length).Insert(startIndex, replacement);
// Result: "Replace part of portion string"

In-place string replacement in C#: Replacing part of a string in-place using a StringBuilder.

StringBuilder sb = new StringBuilder("Replace in-place");
sb.Replace("in-place", "inline");
string result = sb.ToString();
// Result: "Replace inline"

Conditional string replacement in C#: Replacing a substring conditionally.

string input = "Replace conditionally";
string target = "conditionally";
string result = input.Contains(target) ? input.Replace(target, "conditionally replaced") : input;
// Result: "Replace conditionally replaced"