Web Programming Step by Step

Lecture 8
More PHP; File I/O

Reading: 5.4

Except where otherwise noted, the contents of this presentation are Copyright 2010 Marty Stepp and Jessica Miller.

Valid XHTML 1.1 Valid CSS!

5.4: Advanced PHP Syntax

NULL

$name = "Victoria";
$name = NULL;
if (isset($name)) {
	print "This line isn't going to be reached.\n";
}

Arrays (5.4.3)

$name = array();                         # create
$name = array(value0, value1, ..., valueN);

$name[index]                              # get element value
$name[index] = value;                      # set element value
$name[] = value;                          # append
$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)

Array functions

function name(s) description
count number of elements in the array
print_r print array's contents
array_pop, array_push,
array_shift, array_unshift
using array as a stack/queue
in_array, array_search, array_reverse,
sort, rsort, shuffle
searching and reordering
array_fill, array_merge, array_intersect,
array_diff, array_slice, range
creating, filling, filtering
array_sum, array_product, array_unique,
array_filter, array_reduce
processing elements

Array function example

$tas = array("MD", "BH", "KK", "HM", "JP");
for ($i = 0; $i < count($tas); $i++) {
	$tas[$i] = strtolower($tas[$i]);
}                                 # ("md", "bh", "kk", "hm", "jp")
$morgan = array_shift($tas);      # ("bh", "kk", "hm", "jp")
array_pop($tas);                  # ("bh", "kk", "hm")
array_push($tas, "ms");           # ("bh", "kk", "hm", "ms")
array_reverse($tas);              # ("ms", "hm", "kk", "bh")
sort($tas);                       # ("bh", "hm", "kk", "ms")
$best = array_slice($tas, 1, 2);  # ("hm", "kk")

The foreach loop (5.4.4)

foreach ($array as $variableName) {
	...
}
$stooges = array("Larry", "Moe", "Curly", "Shemp");
for ($i = 0; $i < count($stooges); $i++) {
	print "Moe slaps {$stooges[$i]}\n";
}
foreach ($stooges as $stooge) {
	print "Moe slaps $stooge\n";  # even himself!
}

Splitting/joining strings

$array = explode(delimiter, string);
$string = implode(delimiter, array);
$s  = "CSE 190 M";
$a  = explode(" ", $s);     # ("CSE", "190", "M")
$s2 = implode("...", $a);   # "CSE...190...M"

Example with explode

contents of input file names.txt
Martin D Stepp
Jessica K Miller
Victoria R Kirst
foreach (file("names.txt") as $name) {
	$tokens = explode(" ", $name);
	?>
	<p> author: <?= $tokens[2] ?>, <?= $tokens[0] ?> </p>
	<?php
}

author: Stepp, Marty

author: Miller, Jessica

author: Kirst, Victoria

Query strings and parameters (6.1.1)

URL?name=value&name=value...
http://www.google.com/search?q=Obama

http://example.com/student_login.php?username=stepp&id=1234567

6.1: Parameterized Pages

Query parameters: $_REQUEST (6.4.2)

$user_name = $_REQUEST["username"];
$id_number = (int) $_REQUEST["id"];
$eats_meat = FALSE;
if (isset($_REQUEST["meat"])) {
	$eats_meat = TRUE;
}

Functions (5.4.1)

function name(parameterName, ..., parameterName) {
	statements;
}
function bmi($weight, $height) {
	$result = 703 * $weight / $height / $height;
	return $result;
}

Calling functions

name(expression, ..., expression);
$w = 163;  # pounds
$h = 70;   # inches
$my_bmi = bmi($w, $h);

Variable scope: global and local vars

$school = "UW";                   # global
...

function downgrade() {
	global $school;
	$suffix = "(Wisconsin)";        # local

	$school = "$school $suffix";
	print "$school\n";
}

Default parameter values

function name(parameterName = value, ..., parameterName = value) {
	statements;
}
function print_separated($str, $separator = ", ") {
	if (strlen($str) > 0) {
		print $str[0];
		for ($i = 1; $i < strlen($str); $i++) {
			print $separator . $str[$i];
		}
	}
}
print_separated("hello");        # h, e, l, l, o
print_separated("hello", "-");   # h-e-l-l-o

5.4: PHP File Input

PHP file I/O functions (5.4.5)

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

Reading/writing files

contents of foo.txt file("foo.txt") file_get_contents("foo.txt")
Hello
how r u?

I'm fine
array(
	"Hello\n",     # 0
	"how r u?\n",  # 1
	"\n",          # 2
	"I'm fine\n"   # 3
)
"Hello\n
how r u?\n      # a single
\n              # string
I'm fine\n"

Reading/writing an entire file

# reverse a file
$text = file_get_contents("poem.txt");
$text = strrev($text);
file_put_contents("poem.txt", $text);

Appending to a file

# add a line to a file
$new_text = "P.S. ILY, GTG TTYL!~";
file_put_contents("poem.txt", $new_text, FILE_APPEND);
old contents new contents
Roses are red,
Violets are blue.
All my base,
Are belong to you.
Roses are red,
Violets are blue.
All my base,
Are belong to you.
P.S. ILY, GTG TTYL!~

The file function

# display lines of file as a bulleted list
$lines = file("todolist.txt");
foreach ($lines as $line) {        # for ($i = 0; $i < count($lines); $i++)
	print "<li>$line</li>\n";
}

Unpacking an array: list

list($var1, ..., $varN) = array;
contents of input file personal.txt
Marty Stepp
(206) 685-2181
570-86-7326
list($name, $phone, $ssn) = file("personal.txt");
...

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 example

# 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 "<p>I just reversed " . basename($poemfile) . "</p>\n";
}

scandir example

<ul>
	<?php
	$folder = "taxes/old";
	foreach (scandir($folder) as $filename) {
		print "<li>$filename</li>\n"
	}
	?>
</ul>
  • .
  • ..
  • 2007_w2.pdf
  • 2006_1099.doc