How to extract a substring from a string in PHP until it reaches a certain character?

Question

I have part of a PHP application which assess a long string input by the user, and extracts a number which always begins 20 characters into the string the user supplies.

The only problem is that I don't know how long the number for each user will be, all I do know is the end of the number is always followed by a double quote (").

How can I use the PHP substring function to extract a substring starting form a specific point, and ending when it hits a double quote?

Thanks in advance.

Answer 1

You can use strpos to get the first position of " from the position 20 on:

$pos = strpos($str, '"', 20);

That position can then be used to get the substring:

if ($pos !== false) {
    // " found after position 20
    $substr = substr($str, 20, $pos-20-1);
}

The calculation for the third parameter is necessary as substr expects the length of the substring and not the end position. Also note that substr returns false if needle cannot be found in haystack.

Answer 2

$nLast = strpos($userString , '"');
substr($userString, 0, $nLast);