Checking a String with a Regex in PHP

The capabilities of regular expressions are far from exhausted by search and replace. There is also the function preg_match, which checks if a string contains a match with the regex. The first parameter of the function takes the regular expression, and the second - the string to search in.

In this case, if there are many matches, - the function will find only the first one and finish its work. Therefore, the function outputs either 1, or 0 and is used to answer the question 'is the sought-after present in the string or not'. Returns one - means yes (and how many times - is unclear), returns zero - means no.

Let's look at some examples. Let's check, if the string contains a substring consisting of the letter 'a', repeated one or more times:

php<?php
  echo preg_match('#a+#', 'eee aaa bbb'); // outputs 1
?>

And now our string does not contain the sought-after, and the function will output 0:

php<?php
  echo preg_match('#a+#', 'eee bbb'); // outputs 0
?>