需要一个正则表达式来匹配单个字符或单词，但不应该匹配子字符串

Question

I have the following sample text:

I want to replace all instances of ; , : , , , . , and , a , an , the with pipe | symbol.

So the output should be something like:

I tried with the following regex but i am not getting a generic regex which matches for all:

"\/(^|\\W);($|\\W)\/",
"\/(^|\\W):($|\\W)\/",
"\/(^|\\W),($|\\W)\/",
"\/(^|\\W).($|\\W)\/",
"\/(^|\\W)and($|\\W)\/",
"\/(^|\\W)a($|\\W)\/",
"\/(^|\\W)an($|\\W)\/",
"\/(^|\\W)the($|\\W)\/",
"\/(^|\\W)said($|\\W)\/",

Also tried:

(?<=\s)(;.)
(?<=\s)(:.)
(?<=\s)(,.)
(?<=\s)(..)
(?<=\s)(an.)
(?<=\s)(and.)

But does not work, please help. Please note a search for a should match the portion

with a light emitting

but should not match

extraction

. Similar behavior required for others.

Answer 1

Although there are some ambiguous cases, by using below regex you are able to match those characters. Be careful about word boundary and non-word boundary meta-characters:

[;.,:]\B|\b(?:an?d?|the)\b

Live demo