Regular Expression to match string starting with a specific word

Question

How do I create a regular expression to match a word at the beginning of a string   We are looking to match stop at the beginning of a string and anything can follow it   For example the expression should match   stop stop random stopping   Thanks

User · Answer

Like  SharadHolani said  This won t match every word beginning with  stop     Only if it s at the beginning of a line like  stop going    Waxo gave the right answer   This one is slightly better  if you want to match any word beginning with  stop  and containing nothing but letters from A to Z    bstop a-zA-Z   b   This would match all     stop  1       stop random  2       stopping  3       want to stop  4       please stop  5    But     stop a-zA-Z      would only match  1  until  3   but not  4   amp   5

User · Answer

If you wish to match only lines beginning with stop use   stop   If you wish to match lines beginning with the word stop followed by a space   stop s   Or  if you wish to match lines beginning with the word stop but followed by either a space or any other non word character you can use  your regex flavor permitting    stop W   On the other hand  what follows matches a word at the beginning of a string on most regex flavors  in these flavors  w matches the opposite of  W     w   If your flavor does not have the  w shortcut  you can use    a-zA-Z0-9     Be wary that this second idiom will only match letters and numbers  no symbol whatsoever   Check your regex flavor manual to know what shortcuts are allowed and what exactly do they match  and how do they deal with Unicode

User · Answer

stop  a-zA-Z       Will match any stop word  stop  stopped  stopping  etc   However  if you just want to match  stop  at the start of a string    stop    will do  D

User · Answer

If you want to match anything that starts with  stop  including  stop going    stop  and  stopping  use    stop   If you want to match the word stop followed by anything as in  stop going    stop this   but not  stopped  and not  stopping  use    stop W

User · Answer

Try this     stop       Explanation      charachters delimit the regular expression  i e  they are not part of the Regex per se    means match at the beginning of the line   followed by   means match any character      any number of times       means to the end of the line   If you would like to enforce that stop be followed by a whitespace  you could modify the RegEx like so     stop s          s means any whitespace character   following the  s means there has to be at least one whitespace character following after the stop word   Note  Also keep in mind that the RegEx above requires that the stop word be followed by a space  So it wouldn t match a line that only contains  stop

User · Answer

If you want to match anything after a word stop an not only at the start of the line you may use    bstop   b - word followed by line    Or if you want to match the word in the string use  bstop a-zA-Z   - only the words starting with stop    Or the start of lines with stop  stop a-zA-Z   for the word only - first word only The whole line  stop   - first line of the string only  And if you want to match every string starting with stop including newlines use     stop   s - multiline string starting with stop

User · Answer

I d advise against a simple regular expression approach to this problem  There are too many words that are substrings of other unrelated words  and you ll probably drive yourself crazy trying to overadapt the simpler solutions already provided   You ll want at least a naive stemming algorithm  try the Porter stemmer  there s available  free code in most languages  to process text first  Keep this processed text and the preprocessed text in two separate space-split arrays  Make sure each non-alphabetical character also gets its own index in this array  Whatever list of words you re filtering  stem them also    The next step would be to find the array indices which match to your list of stemmed  stop  words  Remove those from the unprocessed array  and then rejoin on spaces   This is only slightly more complicated  but will be much more reliable an approach   If you ve got any doubts on the value of a more NLP-oriented approach  you might want to do some research into clbuttic mistakes

User · Answer

If you want the word to start with  stop   you can use the following pattern     stop     This will match words starting with stop followed by anything

[regex] Regular Expression to match string starting with a specific word

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