Regular expression to match words ending in either y or z, but not both.

you can use

\b\w*[yz]\b(?<!yz)

      

        
        
        
      

    

or - if the word cannot end with yz

OR zy

:

\b\w*[yz]\b(?<!yz|zy)

      

        
        
        
      

    

It matches any word ending in y

or z

, but not yyz

(or with (?<!yz|zy)

, not those ending in yz

or zy

).

See regex demo

Note that the \b

inside of the square brackets is not a word boundary, but an escape sequence that matches the escape sequence.

Template details

• \b
  
  - upper word border
• \w*
  
  - word symbols + + + (letters, numbers or _
  
  , it can be customized to match letters with [^\W\d_]*
  
  )
• [yz]
  
  - a y
  
  orz
  
  
• \b
  
  - final word boundary
• (?<!yz)
  
  - negative lookbehind that does not match if there is a sequence of yz
  
  char immediately before the current location.

EDIT : now that all Perl, Python and Java tags are removed, this might also catch the attention of people who would like to use regex in VBA, C ++std::regex

(default is ECMAScript5) or JavaScript whose regex engines ( ECMA-5 standard ) do not support lookbehinds, but do support lookaheads.

you can use

/\b(?!\w*(?:yz|zy)\b)\w*[yz]\b/

      

        
        
        
      

    

See regex demo .

More details

• \b
  
  - upper word border
• (?!\w*(?:yz|zy)\b)
  
  - negative result that is executed immediately after finding a word boundary, and it will fail if there is either yz
  
  or or a zy
  
  final word boundary after 0 + word characters
• \w*
  
  - use of word symbols + +
• [yz]
  
  - y
  
  orz
  
  
• \b
  
  is the final word boundary.