PHP Regular Expression not matching

Question

I have a really simple PHP regular expression that isn't returning as a match, as seen below.

if(preg_match('[0-9]{3}','123')){
    echo "match";
}
else{
    echo "nope";
}

This should check if the string '123' matches the pattern '[0-9]{3}', which of course it does - however it's not completing the true condition and is instead echoing "nope".

I've also tried:

if(preg_match('[0-9]{3}' '123') == '1'){
    echo "match";
}
else{
    echo "nope";
}

Any ideas? Do I need to configure my server or enable a regex property / library or something?

Avinash Raj · Accepted Answer · 2015-01-15 17:22:51Z

5

You forget to add the php delimiters.

if(preg_match('~[0-9]{3}~','123')){

answered Jan 15, 2015 at 17:22

Avinash Raj

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7 Comments

donald123 Over a year ago

delimiters can anything ~ @ | ... for understanding

Niet the Dark Absol Over a year ago

Recommend using (...) as delimiters. I do this for two reasons: 1) It subtly reminds me that index 0 of the matched set is the whole match, and 2) they come in matching pairs so you never, ever need to worry about escaping delimiters in the regex itself.

Andy Lester Over a year ago

Probably best to use /.../ since that's what most people, at least from the Unix world, expect to see as delimiters.

Avinash Raj Over a year ago

@AndyLester but it have some problems. I think you need to escape the forward slashes..

Jonny 5 Over a year ago

Also prefer ~ as delimiter :) Of course it depends on what you're mostly writing the patterns for. There are possibly more cases in general (paths, links,...) where one matches a / than matching literal ~. @NiettheDarkAbsol 2.) For me such as '~$([^)]+)$~' is better readable than '($([^$]+)\))' eg to capture parenthesized stuff to $1.

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