Question

I have a string that I would like to validate a certain pattern for: Here’s the string:

[alphanumeric characters at the start of the line, then->] ?,?,?,?,?[lines end with: vb|cr|crlf]

What I’d like to achieve as a validation would be to ensure the following, pertaining to the “?,?,?,?,?” string:

1. Validation should return false if there are more than one question mark (?) or comma (,) together. An example that should cause failure would be: ?? <or> ,, <or> ??? <or> ,,,

2. Validation at the end of the line should just be for question marks (?) and commas (,). No other characters…

3. The last value in the string in question (which, again, is: "?,?,?,?,?") should always be a question mark and not a comma.

4. Similarly, the start of this string should always be a question mark and not a comma.

I’m hoping that this would be possible with the preg_match function, but please let me know if it isn’t possible.

Answer 1

How about this regex? It matches your test case.

/^[A-Za-z0-9 ()]+(\?(?:,\?)+)?vb\|cr\|crlf$/i
                             ^
                             Added this question mark

Now, the regex matches:

1. Read )Aloud Your Alphabet(?,?,?vb|cr|crlf
2. Read )In Silence Respect(vb|cr|crlf

Demo (This demo omits the above added question mark)