Other String Comparison Functions

While the strcmp() function is the most commonly used string comparison function in PHP, there are other
string comparison functions offered:

• strcasecmp -
               This string comparison function is equivalent to the strcmp() function except that it is
not case sensitive.

<?php
function chk_emails($input1, $input2) {
if (! strcasecomp($input1, $input2)) {
print "E-mails are the same, proceed<br>";
}else {
print "E-mails are not equal<br>";
}
}
chk_emails("jones@mysql.com","Jones@MySQL.com");
// strcasecmp is case-insensitive and thus these two e-mails
// are the same
?>


• strspn -
              The strspn() function compares two strings to determine how closely related they are to each
other. This is accomplished by returning the length of the first string containing characters that are
also located in the second string.

<?php
function passwd_diff($n_passwd, $o_passwd) {
if (strspn($n_passwd, $o_passwd) > (strlen($o_passwd) *.75))
{
print "New password must be noticeably different from
the old password<br>";
}else {
print "The new password is acceptable<br>";
}
}
passwd_diff ("mydogskip","mydogskippy");
// The characters in the new password and old password are

// too similar to be allowed

passwd_diff ("myfriendskip","mydogskippy");

// The characters are different enough between the two

// passwords to be considered acceptable

?>

• strcspn -
                 The strcspn() function is similar to the strspn() function in that it compares two strings to
determine how closely related they are to each other. However, rather than giving a number related to
the similarities it looks at each character from left to right and identifies the first segment in the first
string containing characters not in the second string.

<?php

$alphabet1 = "abcdefghijklmnopqrstuvwxyz";

$alphabet2 = "ghijklmnopqrstuvwxyz";

print strcspn($alphabet1, $alphabet2);

?>