Regular expression to match a word or its prefix

Question

I want to match a regular expression on a whole word   In the following example I am trying to match s or season but what I have matches s  e  a  o and n      s season    How do I make a regular expression to match a whole word

User · Answer

defines a character class  So every character you set there  will match   012  will match 0 or 1 or 2 and  0-2  behaves the same   What you want is groupings to define a or-statement  Use  s season  for your issue   Btw  you have to watch out  Metacharacters in normal regex  or inside a grouping  are different from character class  A character class is like a sub-language    A  will only match   or A  nothing else  No escaping here for the dollar

User · Answer

Square brackets are meant for character class  and you re actually trying to match any one of  s     s  again   e  a  s  again   o and n   Use parentheses instead for grouping    s season    or non-capturing group      s season      Note  Non-capture groups tell the engine that it doesn t need to store the match  while the other one  capturing group does   For small stuff  either works  for  heavy duty  stuff  you might want to see first if you need the match or not  If you don t  better use the non-capture group to allocate more memory for calculation instead of storing something you will never need to use

User · Answer

I test examples in js   Simplest solution - just add word u need inside       var reg    cat   reg test  some cat here     1 test true    result reg test  acatb     2 test true    result     Now if u need this specific word with boundaries  not inside any other signs-letters  We use b marker   var reg     bcat b  reg test  acatb     1 test  false    result reg test  have cat here     2 test true    result   We have also exec   method in js  whichone returns object-result  It helps f g  to get info about place index of our word   var matchResult     bcat b  exec  good cat good    console log matchResult index      5   If we need get all matched words in string sentence text  we can use g modifier  global match     cat good cat good cat  match   bcat b g  length    3    Now the last one - i need not 1 specific word  but some of them  We use   sign  it means choice or    bad dog bad  match   bcat dog b g  length    1

User · Answer

Use this live online example to test your pattern     Above screenshot taken from this live example  https   regex101 com r cU5lC2 1  Matching any whole word on the commandline   I ll be using the phpsh interactive shell on Ubuntu 12 10 to demonstrate the PCRE regex engine through the method known as preg match  Start phpsh  put some content into a variable  match on word   el apollo   foo  phpsh  php gt   content1    badger  php gt   content2    1234  php gt   content3        amp    php gt  echo preg match    w      content1   1  php gt  echo preg match    w      content2   1  php gt  echo preg match    w      content3   0   The preg match method used the PCRE engine within the PHP language to analyze variables   content1   content2 and  content3 with the   w   pattern      content1 and  content2 contain at least one word   content3 does not   Match a specific words on the commandline without word bountaries  el apollo   foo  phpsh  php gt   gun1    dart gun   php gt   gun2    fart gun   php gt   gun3    darty gun   php gt   gun4    unicorn gun    php gt  echo preg match   dart fart     gun1   1  php gt  echo preg match   dart fart     gun2   1  php gt  echo preg match   dart fart     gun3   1  php gt  echo preg match   dart fart     gun4   0   Variables gun1 and gun2 contain the string dart or fart which is correct  but gun3 contains darty and still matches  that is the problem   So onto the next example   Match specific words on the commandline with word boundaries   Word Boundaries can be force matched with  b  see    Regex Visual Image acquired from http   jex im regulex and https   github com JexCheng regulex  Example   el apollo   foo  phpsh  php gt   gun1    dart gun   php gt   gun2    fart gun   php gt   gun3    darty gun   php gt   gun4    unicorn gun    php gt  echo preg match    bdart b  bfart b     gun1   1  php gt  echo preg match    bdart b  bfart b     gun2   1  php gt  echo preg match    bdart b  bfart b     gun3   0  php gt  echo preg match    bdart b  bfart b     gun4   0   The  b asserts that we have a word boundary  making sure   dart   is matched  but   darty   isn t

[regex] Regular expression to match a word or its prefix

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