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IS 118 Introduction to Development Tools

IS 118 Introduction to Development Tools. Chapter 4 String Manipulation and Regular Expressions. Things to Cover. Formatting strings Joining and splitting strings Comparing strings Matching and replacing substrings Using regular expressions This will be done using a Smart Form….

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IS 118 Introduction to Development Tools

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  1. IS 118 Introduction to Development Tools Chapter 4 String Manipulation and Regular Expressions IS 118

  2. Things to Cover • Formatting strings • Joining and splitting strings • Comparing strings • Matching and replacing substrings • Using regular expressions • This will be done using a Smart Form… IS 118

  3. Listing 4.1 <?php //create short variable names $name=$_POST['name']; $email=$_POST['email']; $feedback=$_POST['feedback']; $toaddress = 'feedback@example.com'; $subject = 'Feedback from web site'; $mailcontent = 'Customer name: '.$name."\n" .'Customer email: '.$email."\n" ."Customer comments: \n".$feedback."\n"; $fromaddress = 'From: webserver@example.com'; mail($toaddress, $subject, $mailcontent, $fromaddress); ?> <html> <head> <title>Bob's Auto Parts - Feedback Submitted</title> </head> <body> <h1>Feedback submitted</h1> <p>Your feedback has been sent.</p> </body> </html> IS 118

  4. Listing facts • Normally would check that all fields are filled – this does not! • It also assumes that all fields are okay without extra spaces – Not good • Uses mail function which is: • Bool mail (string to, sy=tring subject, string message, string [addit headers], string [addit parms]) IS 118

  5. A look at the code • $mail content concatenates the customer name, email and comments into a single string • This leads us to formatting strings • Trimming: • trim () – strips off white space from beginning and end • Ltrim () and rtrim () – strips off white spaces from the left or the right. IS 118

  6. More Formatting • Converting text to HTML • nl2br () changes new lines to <br /> • sprintf returns a formatted string • printf () sends a formatted string to the browser • General format is (string format [, mixed args…]) • See table 4.1 for conversion codes • Ex: printf(“total amount of order is %.2f (with shipping %.2f) “, $total, $total_Shipping) • %.2f is format symbol (%), 2 decimals floating point IS 118

  7. More Formatting • Changing case • Srtrtoupper ($subject) changes to uppercase • Strtolower ($subject) to lower case • ucfirst ($subject) first letter to uppercase • Uwords( $subject) first letter of each word to uppercase • Addslashes() and stripsslashes() to take out or add slashes – often for database work IS 118

  8. Joining and splitting strings • explode (string separator, string input) • Splits up the input string into pieces based on the separator. • explode(‘@’, $email) separates an email address into two parts • strtok (string input, string separator) • Splits up input string into pieces but one piece at a time $token = strtok($feedback, ‘ ‘); While ($token !=‘’) { $token – strtok(‘ ‘); echo $token.’<br />’; }; IS 118

  9. More strings functions • Substr ( string string, int start[, int length]); • Substr($test, 0, 4); • Returns the first four characters • Finding strings • strstr(), strchr(), strrchr() • strstr( string haystack, string needle) • Strpos (), strrpos() – similar to strstr() • Replacing strings • str_replace(), substr_replace() • $feedback = str_replace($offcolor, ‘%!@*’, $feedback); IS 118

  10. Regular Expressions • When you want to do more than simple matches done so far we use regular expressions • It describes a pattern in a piece of text • It can use wildcards, (.) to match to a single character • .at => cat, sat, mat, #at would all match • Can control the matching • [a-z]at says match any lowercase letter • [a-zA-Z] says match any lower or upper case letter • [^a-z]at means anything BUT lowercase a-z IS 118

  11. Pre-defined character classes – p122 • [[:alnum:]] Alphanumeric • [[:alpha:]] Alpha only • [[:lower:]] Lower case • [[:upper:]] Upper case • [[:digit:]] Decimal digits • [[:xdigit]] Hexadecimal digits • [[:punct:]] Punctuation • [[:blank:]] Tabs and spaces • [[:space:]] White space characters IS 118

  12. Other • Repetition: [[:alpha:]]+ means at least one alpha character • Sub-expressions: [very]*large matches Large, very large, very very large and more • Counted Sub-expressions: [very](1, 3) very, very very, very very very • Special characters see table 4.4 IS 118

  13. Putting it all together • To check for a validly constructed email address (p125): • ^[a-zA-Z0-9_\-.]+@[a-zA-Z0-9_\-.]+\.[a-zA-Z0-9_\-.]+$ • Means start at the beginning and it must have at least one letter, number, underscore, hyphen or dot. • @ matches the @ • [a-zA-Z0-9_\-.]+ matches then the first part of the host name • The . Matches . • [a-zA-Z0-9_\-.]+$ matches the rest of the name • Regular expression are not as efficient as string expressions but are more flexible and powerful IS 118

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