How to exclude string that begin with a character-CodePudding

I am using regex to match

([A-Za-z2-7\/\\ ]{52})

While any string with 52 characters as the one mentioned above will match the string, I want to exclude strings that begin with : followed by the 52 characters.

I am using regex flavor pcre2 For example while the below string matches the regex I wouldn't want to include it since the 52 characters preceed with a :

C:\Users\abcdef\AppData\Local\abcdefghijklmnopqr\Testmeli_fi

CodePudding user response：

Use

:([A-Za-z2-7\/\\ ]{52})(*SKIP)(*F)|(?1)

See regex proof.

EXPLANATION

--------------------------------------------------------------------------------
  :                        ':'
--------------------------------------------------------------------------------
  (                        group and capture to \1:
--------------------------------------------------------------------------------
    [A-Za-z2-                 any character of: 'A' to 'Z', 'a' to
    7\/\\ ]{52}              'z', '2' to '7', '\/', '\\', ' ' (52
                             times)
--------------------------------------------------------------------------------
  )                        end of \1
--------------------------------------------------------------------------------
  (*SKIP)(*F)              fail the match and restart after failure
--------------------------------------------------------------------------------
  |                        or
--------------------------------------------------------------------------------
  (?1)                       recurse group 1 pattern

CodePudding user response：

You could use an anchor to assert the start of the string:

^[A-Za-z2-7\/\\ ]{52}

See a regex demo.