Web Programming Step by Step, 2nd Edition

Lecture 8: File I/O

Reading: 5.4

Except where otherwise noted, the contents of this document are Copyright 2012 Marty Stepp, Jessica Miller, and Victoria Kirst. All rights reserved. Any redistribution, reproduction, transmission, or storage of part or all of the contents in any form is prohibited without the author's expressed written permission.

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5.4: Advanced PHP Syntax

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

5.4: PHP File Input

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

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"

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 $line;
}

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, $ssn) = file("personal.txt");
...
list($area_code, $prefix, $suffix) = explode(" ", $phone);

Reading directories

function description
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")
scandir returns an array of all file names in a given directory
(returns just the file names, such as "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 "I just reversed " . basename($poemfile) . "\n";
}

scandir example

<ul>
	<?php foreach (scandir("taxes/old") as $filename) { ?>
		<li>I found a file: <?= $filename ?></li>
	<?php } ?>
</ul>
  • .
  • ..
  • 2007_w2.pdf
  • 2006_1099.doc

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!~