Extracting Substrings Bounded by Characters in PHP

Extracting phrases bounded by specific characters from a string is a common programming task. PHP provides a convenient solution for this through regular expressions.

Consider the following string:

$String = "[modid=256]";

To extract the portion between the equal sign (=) and the closing square bracket (]), you can use the following code:

$input = $String;
preg_match('~=(.*?)]~', $input, $output);
echo $output[1]; // 256

In this code, the preg_match() function is used to search for the pattern '=(.*?)]' within the $input string. This pattern consists of:

• The first character = to match the equal sign.
• The (.*?) group, which matches any sequence of characters except newlines. The question mark (?) makes it non-greedy, matching as few characters as possible.
• The final character ] to match the closing square bracket.

If the pattern is found in the string, the matching substring is stored in the $output array at index 1.