Replacing \ with \\

You need to escape backslashes or use a verbatim string literal, and also understand that strings are immutable - Replace doesn't change the existing string, it returns a new string:

// Escaping with an extra backslash
updatedString = s.Replace("\\", "\\\\");

// Using a verbatim string literal
updatedString = s.Replace(@"\", @"\\");

For more information on escaping and verbatim string literals, see my strings article.

You need to use the @ character in front of your string literals to ensure that they're taken as verbatim strings and your slashes not interpreted as escape characters. You can also "escape" the \ character but using an additional \.

For example:

string s1 = @"\";
string s2 = @"\\";
string s3 = updatedString.Replace(s1,s2);


string s1 = "\\";
string s2 = "\\\\";
string s3 = updatedString.Replace(s1,s2);

You need to either escape your backslashes, or use string literals, so try:

string Method1(string s) 
    return s.Replace(@"\", @"\\");


string Method1(string s) 
    return s.Replace("\\", "\\\\");

There are also other problems with your code - you can initialise variables when you declare them:

string upadtedString = s;

The Replace method will not change anything if there are no \ to be found, therefore there is no need for if (s.Contains("\")).

Strings are immutable (Do not change) so you need to use string replaced = original.Replace(...); rather than expecting orginal.Replace(...) to change original in place.

You can declare strings directly into the method call rather than using s1 and s2.

string Method1(string s) 
    return s.Replace(@"\", @"\\");


  1. Ariel

    • 2018/8/3

    I tried to break the string into arrays and replace \ with \\ , but couldn't do it, also I tried String.replaceAll something like this ("\" 

  2. Kash

    • 2018/12/13

    Definition of replace with in the Idioms Dictionary. replace with phrase. What does replace with expression mean? Definitions by the largest Idiom Dictionary.

  3. Judson

    • 2015/4/10

    I have escaped "\" and tried escaping '/' but to no use. Nothing happens to the original string. filePath = abc\\xyz(not after escaping two \\, 

  4. Dennis

    • 2021/5/30

    Synonyms for replacing with include exchanging, swapping, switching, substituting, using instead, trading, swopping, swapping over, supplanting and using in preference to. Find more similar words at!

  5. Gonzales

    • 2016/3/29

    There are two ways to go about replacing \\ with \ or unescaping backslash escaped strings in Python. First is using literal_eval to 

  6. Kairo

    • 2020/11/22

    Two types of objects can follow replace with and replace by -- the means / method of replacement or the new content. I would say there is a bias for using by to indicate means and with to indicate the substituted content, but I don't think this is an absolute rule: an example of the former: Replace numbers by doubling them.

  7. Juan

    • 2015/11/30

    You can quickly find and replace text strings in the current PhpStorm handles replacing in the multi-line selection the same way.

  8. Cook

    • 2018/4/7

    Nov 20, 2010. #3. If you are referring to replacing something that is broken, old, or not working/inoperative, then you replace it with a new one. If you are referring to filling the role of someone or something with a substitute, then it is ' replaced by'. "Human bank tellers have all but been replaced by ATMs."

  9. Atticus

    • 2020/8/4

    Enter a search string in the top field and a replace string in the bottom field. Regex search and replace fields. Click the Regex icon to enable 

  10. Jacoby

    • 2018/6/1

    5878. Both with and by may be used together with the verb replace. These are the most common structures: Active: something/somebody replaces something/somebody. Computers cannot replace teachers. A new version will soon replace the current software. Mrs Evans replaced the previous manager. Active: replace something/somebody with something/somebody.

  11. Mac

    • 2016/3/25

    Definition of replace · 1 : to restore to a former place or position replace cards in a file · 2 : to take the place of especially as a substitute or successor · 3 

  12. Darwin

    • 2018/7/11

    Learn some regular expression strategies for replacing tokens in strings. When we need to find or replace values in a string in Java, 

  13. Holden

    • 2017/7/10

    str_replace(string, pattern, replacement) str_replace_all(string, pattern, colour names with their hex values. colours <- str_c("\\b", colors(), "\\b", 

  14. Flynn

    • 2019/12/17

    Returns a new string obtained by replacing each substring of this char sequence that matches the given regular expression with the given replacement.

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