Regex Replacement

Question

I have a string:

users/554983490\/Another+Test+/Question????\/+dhjkfsdf/

How would i write a RegExp that would match all of the forward slashes NOT preceded by a back slash?

EDIT: Is there a way to do it without using a negative lookbehinds?

Answer 1

You can use this :

/(?<!\\)\//

This is called a negative lookbehind.

I used / as the delimiters

(?<!   <-- Start of the negative lookbehind (means that it should be preceded by the following pattern)
  \\     <--  The \ character (escaped)
)      <-- End of the negative lookbehind
\/     <-- The / character (escaped)

Answer 2

If your regular expressions support negative lookbehinds:

/(?<!\\)\//

Otherwise, you will need to match the character before the / as well:

/(^|[^\\])\//

This matches either the start of a string (^), or (|) anything other than a \ ([^\\]) as capture group #1 (). Then it matches the literal / after. Whatever character was before the / will be stored in the capture group $1 so you can put it back in if you are doing a replace....

Example (JavaScript):

'st/ri\\/ng'.replace(/(^|[^\\])\//, "$1\\/");
// returns "st\/ri\/ng"