how to write one regular express for the word cpp or h?

Question

how to write one regular express for cpp or h? I want to match the word cpp or h?

Which regex engine are you using? That doesn't seem right. In any case, just use parentheses: `(cpp)|(h)` — tckmn, Jul 18 '14 at 05:58

Avinash Raj · Answer 1 · 2014-07-18T06:10:04.563

0

Use a non-capturing group,

(?:cpp|h)

Add word boundaries inorder to match cpp or h present just before and after to a non-word character.

\b(?:cpp|h)\b

edited Jul 18 '14 at 06:10

answered Jul 18 '14 at 06:03

Avinash Raj

score 0 · Answer 2 · edited May 23 '17 at 11:50

Option 1: validate that a string is exactly cpp or h.

For this, use:

^h|cpp$

Explanation

The reason why cpp|h "matches" cph is that the engine is able to match the h in cph. If you inspect whether a match is found, it will return True.
The ^ anchor asserts that we are at the beginning of the string
h|cpp matches h OR (|) cpp
The $ anchor asserts that we are at the end of the string

Option 2: match h or cpp as independent words within text

For this, use:

\b(?:h|cpp)\b

which is essentially the same as the second option in Avinash's answer.

2 Answers2