YOUR WEBSITE

Case sensitivity is an issue that the programmer (and the end user) must deal with. Everything from commands to passwords are affected by case sensitivity. In PHP there are four functions that provide the tools to deal with the case sensitivity issue by allowing the string case to be manipulated. • strtolower -                  This string case manipulation function converts all characters that are uppercase characters to lowercase characters. <?php $text = "MySQL http://WWW.MYSQL.COM"; print strtolower($text); // Returns "mysql http://www.mysql.com"; ?> • strtoupper -  This string case manipulation function converts all characters that are lowercase characters to uppercase characters. <?php $text = "MySQL http://WWW.MYSQL.COM"; print strtoupper($text); // Returns "MYSQL HTTP://WWW.MYSQL.COM"; ?> • ucfirst -                   This string case manipulation function converts only the first character of the

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_p

Following the password example just shown, there are many web sites today that force a person to type there password in twice to make sure that they truly are setting it to what they want (the chances of typing it identically wrong twice is very low). This is accomplished using such tools as strcmp() which is a built-in to PHP. <?php Function chk_passwds($input1, $input2) { if (strcomp($input1, $input2) = 0) { print "Passwords are equal, proceed<br>"; }else { print "Passwords are not equal<br>"; } } chk_passwds("doggy1", "Doggy1"); // strcmp is case-sensitive and thus these passwords are not equal ?> The strcomp() function has three possible results: 0 means the two strings are equal, -1 means that the first string is less than the second string and 1 means that the second string is less than the first string. In the example above, all that needs to be tested is if they are equal. It is not necessary to kno

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");

• preg_split -                     This Perl-style function is equivalent to the split() function previously discussed with the exception of allowing Perl-style regular expressions. The third optional component of the preg_split() function can be entered to limit the number of changes that take place. Failing to enter a numeric limit (or a -1), ensures that there is no limit on the changes that can take place. <?php $csv_text = "5, \"Amsterdam\", \"NLD\", \"Noord-Holland\", 731200"; $csv_array = preg_split("/\,/",$csv_text); foreach ($csv_array as $csv_column) { print "$csv_column<br>"; } ?> The script above creates an array called $csv_row that contains the following element: [0] = 5, [1]="Amsterdam", [2]="NLD", [3]="Noord-Holland", [4]=731200). The foreach iterative control statement prints each of these elements on the screen on their own lines. A third component

• preg_replace_callback() -                                            With preg_replace(), the function itself is responsible for handling the replacement procedure. With preg_replace_callback(), the handling of the replacement procedure is handed off to another function to take care of. The syntax is identical to preg_replace() except where the replacement text would be located, a function name is present. This function is responsible for handling any of the replacement changes to the text that matches the pattern searched. <?php $text = "Dear <pnm>S</pnm>Ortiz,<br>&nbsp;&nbsp;&nbsp;&nbsp;I would like to thank you and <pnf>F</pnf>Picard for taking the time in talking to me today. Please feel free to contact me if you have any additional questions.<br>Sincerely,<br><pnm>E</pnm>Bob Riker"; function proper_name_m($matches) { $titles = array( 'E' => 'Mr. ', 'S'

• preg_replace() -                              This Perl-syntax function is equivalent to the ereg_replace() function. This function works by replacing all occurrences of the pattern searched with the replacement characters and then returns the modified result. The fourth parameter is optional, but when a number is entered it determines how many occurrences of the pattern searched will be replaced. If no number is entered, all occurrences of the search pattern will be replaced. <?php $url = "MySQL http://www.mysql.com"; print preg_replace("/http:\/\/(.*)/","<a href=\"\${0}\">\${0}</a>", $url); ?> The script above changes the http reference to be replaced with the HTML code required to create a web link. The three components of this function include the pattern to search for ("/http:\/\/(.*)/"), the replacement string ("<a href=\"\${0}\">\${0}</a>") and then finally the