Comparing Strings

As stated, PHP has poweful regular expressions that provide programmers with the tools necessary to
complete difficult searching tasks. In addition to this regular expression capability, PHP provides built-in
functionality for performing a wide range of string-specific tasks. Many of these tasks are based on string
comparison operations.

String Length

One of the simplest comparison operators of strings is determining if the lengths are equivalent. This
involves determining the length of the strings and then acting upon those lengths. The length function
built-in to PHP is strlen() and is one of the more widely used string expressions.

<?php
function chk_passwd($input) {
if (strlen($input) < 7) {
print "Password is too short";
} else if (strlen($input) > 10) {
print "Password is too long";
}else {
print "Password is the proper length, proceed<br>";
}
}
chk_passwd("doggy1");
chk_passwd("Diabolical");
chk_passwd("rst 4567");
chk_passwd("run-^$#&");
chk_passwd("mydogspotruns");
?>
In the above example, the length of the password is the only test being evaluated. Of course, this would not
be acceptable by itself; however, it does show how length can be used as a string test.