Question

I need to be able to search within a string and find out if [topic] is equal to a number and grab that number only from within the string.

For example, a string like so:

[topic]=10[board]=1

should return 10

But a string like this:

[topic][board]=1

should return 0 or false

A string like this:

[topic]=1.5[board]=2

should return 1, cause we need to round down floor()

Also, we aren’t worried about negative numbers, cause this will never happen.

How can I do this to just grab the number only, rounding down, from these types of strings that look like this, only if [topic] is present in the string and defined with an equal sign.

Thanks guys 🙂

Answer 1

The idea below uses preg_match and a regular express that looks for the word "topic" inside square brackets followed by an equal sign and one of more numbers. Before the matches, I set the default value of the topic (false in this case). If a topic is found, I then convert it to an integer.

This will ignore the decimal point and any numbers that follow as \d only contains the numbers 0 through 9.

Example:

<?php 

$string = '[topic]=10[board]=1';

$topic = false;
if (preg_match('/\[topic\]=(?P<topic>\d+)/', $string, $matches)) {
    $topic = (int)$matches['topic'];
}

var_dump($topic);