I can count to $i!
\n"; } ?> HTML best PHP style is to minimize print/echo statements in embedded PHP code but without print, how do we insert dynamic content into the page?"> "\n"; print " \n"; print "I can count to $i!
\n"; } ?> HTML best PHP style is to minimize print/echo statements in embedded PHP code but without print, how do we insert dynamic content into the page?">
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More on PHP: Arrays, Functions and Files
CMPT241 Web Programming More on PHP: Arrays, Functions and Files
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Printing HTML tags in PHP = bad style
print "<!DOCTYPE html>"\n"; print " <head>\n"; print " <title>My web page</title>\n"; ... for ($i = 1; $i <= 10; $i++) { print "<p> I can count to $i! </p>\n"; } ?> HTML best PHP style is to minimize print/echo statements in embedded PHP code but without print, how do we insert dynamic content into the page?
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PHP expression blocks The answer is 42 output
<?= expression ?> PHP <h2> The answer is <?= 6 * 7 ?> </h2> PHP The answer is output PHP expression block: a small piece of PHP that evaluates and embeds an expression's value into HTML <?= expression ?> is equivalent to: useful for embedding a small amount of PHP (a variable's or expression's value) in a large block of HTML without having to switch to "PHP-mode" <?php print expression; ?> PHP
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Expression block example
<!DOCTYPE html> <head><title>Embedded PHP</title> </head> <body> <?php for ($i = 99; $i >= 1; $i--) { ?> <p> <?= $i ?> bottles of beer on the wall, <br /> <?= $i ?> bottles of beer. <br /> Take one down, pass it around, <br /> <?= $i - 1 ?> bottles of beer on the wall. </p> } </body> </html> PHP
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Common errors: unclosed braces, missing = sign
... <body> <p>Watch how high I can count: <?php for ($i = 1; $i <= 10; $i++) { ?> <? $i ?> </p> </body> </html> PHP if you forget to close your braces, you'll see an error about 'unexpected $end' if you forget = in <?=, the expression does not produce any output
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Complex expression blocks
... <body> <?php for ($i = 1; $i <= 3; $i++) { ?> <h<?= $i ?>>This is a level <?= $i ?> heading.</h<?= $i ?>> } </body> PHP This is a level 1 heading. This is a level 2 heading. This is a level 3 heading output
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Arrays Append: use bracket notation without specifying an index
$name = array(); # create $name = array(value0, value1, ..., valueN); $name[index] # get element value $name[index] = value; # set element value $name[] = value; # append PHP $a = array(); # empty array (length 0) $a[0] = 23; # stores 23 at index 0 (length 1) $a2 = array("some", "strings", "in", "an", "array"); $a2[] = "Ooh!"; # add string to end (at index 5) PHP Append: use bracket notation without specifying an index Element type is not specified; can mix types
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Arrays $a2 = array("some", "strings", "in", "an", "array");
$a2[100] = "Ooh!"; # add string to end (at index 100) PHP
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Array functions function name(s) description count(a)
number of elements in the array print_r (a) print array's contents array_pop(a), array_push(a,value), array_shift(a), array_unshift(a,value) using array as a stack/queue in_array(value,a), array_search(value,a), array_reverse(a), sort(a), rsort(a), shuffle(a) searching and reordering array_merge(a1,a2,...), array_intersect(a1,a2,...), array_diff(a1,a2), array_slice(a,start,len) creating, filling, filtering array_sum(a), array_product(a), array_unique(a) processing elements
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Array function example
$tas = array("MD", "BH", "KK", "HM", "JP"); for ($i = 0; $i < count($tas); $i++) { $tas[$i] = strtolower($tas[$i]); } $morgan = array_shift($tas); array_pop($tas); array_push($tas, "ms"); array_reverse($tas); sort($tas); $best = array_slice($tas, 1, 2); # subarray PHP Maybe delete the comments that give out the output # ("md", "bh", "kk", "hm", "jp") # ("bh", "kk", "hm") # ("bh", "kk", "hm", "ms") # ("ms", "hm", "kk", "bh") # ("bh", "hm", "kk", "ms") # ("hm", "kk") the array in PHP replaces many other collections in Java list, stack, queue, set, map, ...
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foreach loop You cannot use a foreach loop to modify the elements
foreach ($array as $variableName) { ... } PHP for ($i = 0; $i < count($fellowship); $i++) { print "$fellowship[$i]\n"; } foreach ($fellowship as $fellow) { print "$fellow\n"; } PHP One bad thing with foreach: you cannot change the value of the variable after “as”, you can just assign it a value, it does not have the value in the table You cannot use a foreach loop to modify the elements
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Splitting/joining strings
$array = explode(delimiter, string); $string = implode(delimiter, array); PHP explode and implode convert between strings and arrays $s = “MC CMPT 241"; $a = explode(" ", $s); # ("MC", “CMPT", “241") $s2 = implode("...", $a); # “MC...CMPT...241" PHP
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Example with explode Marty D Stepp Jessica K Miller Victoria R Kirst contents of input file names.txt explode and implode convert between strings and arrays foreach (file("names.txt") as $name) { $tokens = explode(" ", $name); ?> <p> author: <?= $tokens[2] ?>, <?= $tokens[0] ?> </p> <?php } PHP author: Stepp, Marty author: Miller, Jessica author: Kirst, Victoria output
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Unpacking an array: list
list($var1, ..., $varN) = array; PHP $values = array(“mundruid", "18", “f”); ... list($username, $age, $gender) = $values; PHP the list function accepts a comma-separated list of variable names as parameters use this to quickly "unpack" an array's contents into several variables a convenience, so you can refer to $username instead of $values[0], etc.
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Example explode Harry Potter, J.K. Rowling
The Lord of the Rings, J.R.R. Tolkien Dune, Frank Herbert contents of input file books.txt <?php foreach (file(“books.txt") as $book) { list($title, $author) = explode(“,", $book); ?> <p> Book title: <?= $title ?>, Author: <?= $author ?> </p> <?php } ?> PHP
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PHP Arrays Exercise For this exercise, you will use a list of ten of the largest cities in the world. (Please note, these are not the ten largest, just a selection of ten from the largest cities.) Create an array with the following values: Tokyo, Mexico City, New York City, Mumbai, Seoul, Shanghai, Lagos, Buenos Aires, Cairo, London. Print these values to the browser separated by commas, using a loop to iterate over the array. Sort the array, then print the values to the browser in an unordered list, again using a loop. Add the following cities to the array: Los Angeles, Calcutta, Osaka, Beijing. Sort the array again, and print it once more to the browser in an unordered list.
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Multidimensional Arrays
<?php $AmazonProducts = array( array(“BOOK", "Books", 50), array("DVDs", “Movies", 15), array(“CDs", “Music", 20)); for ($row = 0; $row < 3; $row++) { for ($column = 0; $column < 3; $column++) { ?> <p> | <?= $AmazonProducts[$row][$column] ?> <?php } ?> </p> <?php } ?> PHP Maybe delete the comments that give out the output
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Functions parameter types and return types are not written
function name(parameterName, ..., parameterName) { statements; } PHP function bmi($weight, $height) { $result = 703 * $weight / $height / $height; return $result; } PHP parameter types and return types are not written a function with no return statements implicitly returns NULL can be declared in any PHP block, at start/end/middle of code
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Calling functions name(expression, ..., expression); PHP $w = 163; # pounds $h = 70; # inches $my_bmi = bmi($w, $h); PHP if the wrong number of parameters are passed, it's an error
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Default Parameter Values
function print_separated($str, $separator = ", ") { if (strlen($str) > 0) { print $str[0]; for ($i = 1; $i < strlen($str); $i++) { print $separator . $str[$i]; } } PHP print_separated("hello"); # h, e, l, l, o print_separated("hello", "-"); # h-e-l-l-o PHP Any parameters with default values must appear at the end of the list if no value is passed, the default will be used
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Value vs. Reference Parameters
function make_bigger($num){ $num = $num * 2; } $x = 5; make_bigger($x); print $x; PHP function make_bigger(&$num){ $num = $num * 2; } $x = 5; make_bigger($x); print $x; PHP
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Variable scope: global and local vars
$dept = “CMPT"; # global ... function course_number() { global $dept; $suffix = “241"; # local $course = $dept. $suffix; print "$course“; } PHP variables declared in a function are local to that function; others are global if a function wants to use a global variable, it must have a global statement but don't abuse this; mostly you should use parameters
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Note PHP has no narrower scope than function-level.
Variables are destroyed when the function returns Variable scope is completely unrelated to the start and end of PHP <?php ... ?> blocks. function scope_example(){ for ($i = 0; $i < 10; $i++){ print “Hello”; $x = 42; } print $i; print $x; } PHP
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PHP file I/O functions function name(s) category
file, file_get_contents, file_put_contents reading/writing entire files basename, file_exists, filesize, fileperms, filemtime, is_dir, is_readable, is_writable, disk_free_space asking for information copy, rename, unlink, chmod, chgrp, chown, mkdir, rmdir manipulating files and directories glob, scandir reading directories
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Reading from/Writing to a file
# reverse a file $text = file_get_contents("poem.txt"); $text = strrev($text); file_put_contents("poem.txt", $text); PHP file_get_contents returns entire contents of a file as a string file_put_contents writes a string into a file, replacing any prior contents
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file_get_contents If the file doesn’t exist, an empty string is returned and a warning is issued. Suppress the warning message @file_get_contents
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Appending to a file old contents new contents Roses are red,
# add a line to a file $new_text = "P.S. ILY, GTG TTYL!~"; file_put_contents("poem.txt", $new_text, FILE_APPEND); PHP old contents new contents Roses are red, Violets are blue. P.S. ILY, GTG TTYL!~ file_put_contents can be called with an optional third parameter appends (adds to the end) rather than replacing previous contents
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Reading files contents of foo.txt file("foo.txt")
file_get_contents("foo.txt") Hello how are you? I'm fine array( "Hello\n", #0 "how are\n", #1 "you?\n", #2 "\n", #3 "I'm fine\n" #4 ) "Hello\n how are\n you?\n \n I'm fine\n" file returns lines of a file as an array file_get_contents returns entire contents of a file as a string
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The file function # display lines of file as a bulleted list $lines = file("todolist.txt"); foreach ($lines as $line) { ?> <li> <?= $line ?> </li> <?php } ?> PHP file returns the lines of a file as an array of strings each string ends with \n to strip the \n off each line, use optional second parameter: $lines = file("todolist.txt",FILE_IGNORE_NEW_LINES); PHP
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Reading directories function description scandir
returns an array of all file names in a given directory (returns just the file names, such as "myfile.txt") glob returns an array of all file names that match a given pattern (returns a file path and name, such as "foo/bar/myfile.txt") glob can filter by accepting wildcard paths with the * character
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Example for scandir . .. 2009_w2.pdf 2007_1099.doc output <ul>
<?php $folder = "taxes/old"; foreach (scandir($folder) as $filename) { ?> <li> <?= $filename ?> </li> } </ul> PHP annoyingly, the current directory (".") and parent directory ("..") are included in the array don't need basename with scandir because it returns the file's names only . .. 2009_w2.pdf 2007_1099.doc output
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Example for glob glob can match a "wildcard" path with the * character
# reverse all poems in the poetry directory $poems = glob("poetry/poem*.dat"); foreach ($poems as $poemfile) { $text = file_get_contents($poemfile); file_put_contents($poemfile, strrev($text)); print "I just reversed " . } PHP glob can match a "wildcard" path with the * character
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PHP Include File Insert the content of one PHP file into another PHP file before the server executes it Use the include() generates a warning if file not found, but the script will continue execution require() generates a fatal error, and the script will stop Server side includes saves a lot of work. This means that you can create a standard header, footer, or menu file for all your web pages. When the header needs to be updated, you can only update the include file, or when you add a new page to your site, you can simply change the menu file (instead of updating the links on all your web pages).
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include() example <html> <body>
<a href="/default.php">Home</a> <a href="/tutorials.php">Tutorials</a> <a href="/references.php">References</a> <a href="/examples.php">Examples</a> <a href="/contact.php">Contact Us</a> HTML/PHP <html> <body> <div class="leftmenu"> <?php include("menu.php"); ?> </div> <h1>Welcome to my home page.</h1> <p>I have a great menu here.</p> </body> </html> PHP
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Query strings and parameters
URL?name=value&name=value PHP PHP query string: a set of parameters passed from a browser to a web server often passed by placing name/value pairs at the end of a URL above, parameter username has value stepp, and sid has value PHP code on the server can examine and utilize the value of parameters a way for PHP code to produce different output based on values passed by the user
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Query parameters: $_GET
$user_name = $_GET["username"]; $id_number = (int) $_GET["id"]; $eats_meat = FALSE; if (isset($_GET["meat"])) { $eats_meat = TRUE; } PHP $_GET["parameter name"] returns a parameter's value as a string test whether a given parameter was passed with isset
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Object Oriented PHP
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Case Study GRE word of the day
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Homework 7 .php page supporting .css file
Must at least use arrays and files Something similar to the case study (GRE word of the day) we did in class
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Project 3 Due Date: Friday April 3, 2015
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Final Project Team members
Up to 3 people in a team Decide by Tuesday March 31 Start thinking about what project you want to work on Must use PHP, CSS and JavaScript Proposal is due on April 17.
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