Why both of my PHP regexp fail ?

Question

$subject = "SPRINT-1.csv";
$pattern = '/^[a-zA-Z]\-[0-9]\.(csv)+$/';
if(preg_match($pattern, $subject)) {
 echo "Match";
} else {
 echo "NOPE";
}

or

$subject = "SPRINT-1.csv";
$pattern = '/^\w\-\.(csv)+$/';
if(preg_match($pattern, $subject)) {
 echo "Match";
} else {
 echo "NOPE";
}

Answer 1

A character class […] does only describe one single character. So [a-zA-Z] describes one character out of a–z, A–Z. The same applies to \w (that’s also a character class).

You forgot to describe the quantity the characters from that character classes may appear, like:

• ?: zero or one repetition
• *: zero or more repetitions
• +: one or more repetitions

Answer 2

<?
$subject = "SPRINT-1.csv";
$pattern = '/^[a-zA-Z]*\-[0-9]\.csv?$/';
if(preg_match($pattern, $subject)) {
 echo "Match";
} else {
 echo "NOPE";
}
?>

Answer 3

'/^[a-zA-Z]\-[0-9]\.(csv)+$/'; you're missing the quantifier, it should be [a-zA-Z]+ or [a-zA-Z]*.

Try out http://www.regexp.net/ to quickly optimize your regexp.

Answer 4

You can do either:

preg_match_all('/^[a-zA-Z]+\-[0-9]\.csv$/i', 'SPRINT-1.csv', $result);

or

preg_match_all('/^\w+\-\d\.csv+$/i', 'SPRINT-1.csv', $result);

In both case, you forgot the "+" before the letters that match "SPRINT", in the second case, you forgot the number to match "1".

And by the way, you don't need the "+" at the end of the pattern, nor the () around the csv.

But please, make an effort to write a complete question. Posting just code like that is not really handy to understand.

Finally, if you want to test regexp, use a good tool.