preg_match来检索值

Question

I'm using preg_match with PHP 5.6 to retrieve a value from a string. (I'm newb with preg_match)

It goes with this format:

data[SearchForm][somestringhere]

And I need to be able to retrieve the 'somestringhere' value.

I tried doing it this way:

$search_field_pattern   = "/\bdata[SearchForm][[a-zA-Z]]\b/i";
if(preg_match($search_field_pattern, "foo")) {
    debug('foobar!');
}

But it's not working. Can someone give me a hint why it's not working and what I should do to correctly approach this solution?

Thank you.

Answer 1

You may use

$search_field_pattern  = "/\bdata\[SearchForm]\[(\w+)]/i";
if(preg_match($search_field_pattern, "data[SearchForm][somestringhere]", $m)) {
    echo $m[1]; // => somestringhere
}

See the PHP demo

The pattern matches

• \b - a word boundary
• data\[SearchForm]\[ - a literal string data[SearchForm][ (note [ are escaped to match literal [ chars)
• (\w+) - capturing group 1: one or more word chars
• ] - a ] char.

The third argument to preg_match, $m, will hold the results. Since the necessary substring is captured into Group 1, the value is retrieved using $m[1].

---

To get the last substring inside square brackets you may use

if(preg_match("~\[(\w+)](?!.*\[\w+])~s", "data[SearchForm][somestringhere]", $m)) {
    echo $m[1]; // => somestringhere
}

See this PHP demo.

To get the second one, use

if(preg_match("~\[\w+].*?\[(\w+)]~s", "data[SearchForm][somestringhere]", $m)) {
    echo $m[1]; // => somestringhere
}

See yet another PHP demo.