trouble with string message = Regex.Replace(message , "\\", "");

Question

I'm working on replacing the character "\" with a black space.

here is the string,

string message = "http:\/\/www.youtube.com\/v\/"
string message = Regex.Replace(message , "\\", ""); 

but it is not working properly, output message suppose be "http://www.youtube.com/v/" could anyone please help me, thanks!

Answer 1

Your string has no backslashes!

A single backslash inside a string has the special property of "escaping" the next character. As such, your string really contains this:

http://www.youtube.com/v/

Each backslash in your string is escaping the next forward slash. It's not an actual backslash character, and as such searching for that character will result in nothing.

Edit: According to my compiler, \/ is not a valid escape sequence. A forward slash has no special meaning, and as such it cannot be escaped. Your string is technically not valid. Depending on how you got that string, you have different options. Placing an at sign @ before the string:

string message = @"http:\/\/www.youtube.com\/v\/"

will view it literally, escaping nothing (except for a close quote). In that situation, you will have actual backslash characters in your string that can be replaced.

As mentioned in other answers, to replace a backslash you actually need four, like so:

Regex.Replace(message, "\\\\", "");

Answer 2

You do not need to escape forward slash:

string message = "http://www.youtube.com/v/";

is a perfectly good string literal.

The Replace does not work because backslash \ is an escape symbol in both C#'s string literals and regular expressions. Therefore, you need four backslashes to match a single backslash in a string.