Xhtml hyperlink. To download a file from outside the xhtml
directory structure, use the header() function to identify the file
and the readfile() function to send the file contents to the Web
browser.
• The
file_put_contents() function writes or appends a text stringto a file. The file_get_contents() function reads a file into a text
string. The file() function reads a file into an indexed array.
• The stream is used for accessing a resource from which you can
read and to which you can write. The input stream reads data from
a resource such as a file, whereas the output stream writes data to a
resource (again, such as a file).
• The
fopen() function opens a stream to a text file.• A file pointer is a special type of variable that refers to the cur-
rently selected line or character in a file.
• When you finish working with a file stream, you use the
fclose()function to ensure that the file doesn’t keep taking up space in your
computer’s memory.
• The
fwrite() function incrementally writes data to a text file.• The
flock() function prevents multiple users from modifying a filesimultaneously.
284
Comprehension
Check
•
The
the file.
• PHP includes various functions, such as the
fread() andfgets() functions, that allow you to use the file pointer to
iteratively read a text file.
• The
copy() function copies a file. The rename() function renamesor moves a file or directory.
• The
unlink() function deletes files, and the rmdir() functiondeletes directories.
• PHP does not contain a separate command for moving files.
Instead, you can rename the file with the rename() function and
specify a new directory where you want to store the renamed file.
Or, you must copy the file with the copy() function, and then
delete the original file with the unlink() function.
285
Comprehension Check
1.
Which of the following escape sequences is used on
Macintosh platforms? (Select all that apply.)
a. \n
b. \r
c. \n\r
d. \r\n
2.
Which of the following functions sorts directory entries?
a. scandir()
b. readdir()
c. opendir()
d. sortdir()
3.
Explain when you should use file and directory status func-
tions such as file_exists() and is_dir().
What is the value of the enctype attribute for a Web form
that uploads a file?
What is the name of the autoglobal array that contains
uploaded file information?
4.
5.
CHAPTER
5
Working
with Files and Directories
6.
Which
of the following constants can you use with the
file_put_contents()
function
to append data to the end of a
file?
a.
INCLUDE_FILE
286
b.
FILE_USE_INCLUDE_PATH
c.
APPEND
d.
FILE_APPEND
7.
Which
of the following functions reads the contents of a file
into
a string?
a.
file()
b.
file_get_contents()
c.
fread()
d.
readfile()
8.
The
file()
function
automatically recognizes whether the
lines
in a text file end in \n,
\r,
or \n\r. True
or False?
Which
of the following allows you to read data from a
resource
such as a file?
a.
an input stream
b.
an output stream
c.
a pointer
d.
a reference
10.
Which of the following best describes the "w+"
method
argument?
a.
creates and opens the specified file for reading and writ-
ing;
returns
b. opens the specified file for reading and writing and places
the file pointer at the end of the file; attempts to create the
file if it doesn’t exist
c. opens the specified file for writing only and deletes any
existing content in the file; attempts to create the file if it
doesn’t exist
d. opens the specified file for reading and writing and deletes
any existing content in the file; attempts to create the file
if it doesn’t exist
9.
Comprehension
Check
11.
Ais a special type of variable that refers to
the
currently selected character in a file.
a. character pointer
b. line pointer
c. file pointer
d. directory pointer
12. Explain why you should call the fclose() function when you
are finished working with a file.
13. You must open and close a file stream when you use the
file_put_contents() function. True or False?
14. What is the correct syntax for using the fwrite() function to
write a value of “Forestville Foods\n” to a file handle named
$SalesProspects?
a. $SalesProspects = fwrite("Forestville Foods\n");
b. fwrite($SalesProspects, "Forestville Foods\n");
c. fwrite("Forestville Foods\n", $SalesProspects);
d. fwrite("$SalesProspects, Forestville Foods\n");
15. Explain why you should lock files before writing data to
them.
16. Which of the following operational constants can you use
with the
flock() function? (Choose all that apply.)a. LOCK_EX
b. LOCK_NH
c. LOCK_SH
d. LOCK_UH
17. Which of the following functions can you use to iterate
through a text file? (Choose all that apply.)
a. stream_get_line()
b. fgets()
c. fread()
d. readfile()
287
CHAPTER
5
Working
with Files and Directories
18.
Which of the following functions returns a value of
TRUE
when
a file pointer reaches the end of a file?
a.
is_end()
b.
end()
288
c.
eof()
d.
feof()
19.
Which of the following statements creates a directory named
“students”
at the same level as the current directory?
a. mkdir("/students");
b. mkdir("students");
c. mkdir("/students/");
d. mkdir("../students");
20. Explain the two ways in which you can move a file with PHP.
Reinforcement Exercises
Exercise 5-1
In this project, you will create a hit counter script that keeps track
of the number of hits a Web page receives. Ensure that the Projects
directory has read and write permissions for everyone.
1.
Create a new document in your text editor and type the
<!DOCTYPE> declaration, <html> element, document head, and
<body> element. Use the strict DTD and “Hit Counter” as the
content of the <title> element.
Add the following script section to the document body:
<?php
?>
2.
3.
Add the following statement to the script section to declare a
variable named $CounterFile that contains the name of the
file where the hits will be stored:
$CounterFile = "hitcount.txt";
4.
Add the following if statement to the end of the script sec-
tion. The if statement determines whether the hitcount.txt
Reinforcement
Exercises
file
already exists. If it does, the file_get_contents()
func-
tion
retrieves the value from the file and increments it by 1.
if
(file_exists($CounterFile)) {
$Hits
= file_get_contents($CounterFile);
++$Hits;
}
289
5.
Add the following else statement to the end of the script
section. The else statement contains a single statement that
assigns a value of 1 to the $Hits variable in the event that the
hitcount.txt file has not yet been created.
else
$Hits = 1;
6.
Finally, add the following statements to the end of the script
section. The echo statement displays the number of hits and
the if statement updates the value in the hitcount.txt file.
Remember that the file_put_contents() function opens the
file if it already exists or creates the file if it doesn’t exist.
echo "<h1>There have been $Hits hits to this page.
</h1>\n";
if (file_put_contents($CounterFile, $Hits))
echo "<p>The counter file has been updated.
</p>\n";
7.
Save the document as HitCounter.php in the Projects direc-
tory for Chapter 5.
Open HitCounter.php in your Web browser by entering
the following URL: http://<yourserver>/PHP_Projects/
Chapter.05/Projects/HitCounter.php. The first time you open
the Web page, you should see a hit count of 1. Reload the Web
page a few times to see if the count increases.
Close your Web browser window.
8.
9.
Exercise 5-2
In this project, you will create a Web page that allows visitors to your
site to sign a guest book that is saved to a text file. Ensure that the
Projects directory has read and write permissions for everyone.
1.
Create a new document in your text editor and type the
<!DOCTYPE> declaration, <html> element, document head, and
<body> element. Use the strict DTD and “Guest Book” as the
content of the <title> element.
CHAPTER
5
Working
with Files and Directories
2.
Add
the following text and elements to the document body:
<h2>Enter
your name to sign our guest book</h2>
<form
method="POST" action="SignGuestBook.php">
<p>First
Name <input type="text" name="first_name"
/></p>
<p>Last
Name <input type="text" name="last_name"
/></p>
<p><input
type="submit" value="Submit" /></p>
</form>
<p><a
href="ShowGuestBook.php">Show Guest Book
</a></p>
290
3.
Save
the document as GuestBook.html in the Projects direc-
tory
for Chapter 5.
Create
a new document in your text editor and type the
<!DOCTYPE>
declaration,
<html>
element,
document head, and
<body>
element.
Use the strict DTD and “Sign Guest Book” as
the
content of the <title>
element.
Add
the following script section to the document body:
<?php
?>
4.
5.
6.
Add
the following if
statement
to the script section to check
whether
the user filled in the first name and last name fields:
if
(empty($_POST['first_name']) || empty($_
POST['last_name']))
echo
"<p>You must enter your first and last
name. Click your browser's Back button to
return to the Guest Book.</p>\n";
7.
Add the following else clause to the end of the script section.
The statements in the else clause use the fwrite() function
to add visitor names to a text file named guestbook.txt.
else {
$FirstName = addslashes($_POST['first_name']);
$LastName = addslashes($_POST['last_name']);
$GuestBook = fopen("guestbook.txt", "ab");
if (is_writeable("guestbook.txt")) {
if (fwrite($GuestBook, $LastName . ", " .
$FirstName . "\n"))
echo "<p>Thank you for signing our
guest book!</p>\n";
else
echo "<p>Cannot add your name to the
guest book.</p>\n";
}
Reinforcement
Exercises
else
echo
"<p>Cannot write to the file.</p>\n";
fclose($GuestBook);
}
8.
Save the document as SignGuestBook.php in the Projects
directory for Chapter 5.
Create a document named ShowGuestBook.php that dis-
plays the names of visitors who have signed the guest book.
Use the readfile() function to display the contents of the
guestbook.txt file. Note that you will need to use the <pre>
element for Web browsers to recognize the line breaks.
291
9.
10. Open GuestBook.html in your Web browser by enter-
ing the following URL: http://<yourserver>/PHP_Projects/
Chapter.05/Projects/GuestBook.html. Test the form to see if
you can write data to and read data from the guestbook.txt
file.
11. Close your Web browser window.
Exercise 5-3
Create a document with a form that registers bowlers for a bowl-
ing tournament. Use a single text file that saves information for each
bowler on a separate line. Include the bowler’s name, age, and aver-
age, separated by commas. Ensure that the Projects directory has read
and write permissions for everyone.
Exercise 5-4
Create a Web page to be used for storing software development bug
reports in text files. Include fields such as product name and ver-
sion, type of hardware, operating system, frequency of occurrence,
and proposed solutions. Include links on the main page that allow
you to create a new bug report and update an existing bug report.
Ensure that the Projects directory has read and write permissions for
everyone.
Exercise 5-5
Create a Web form for uploading pictures for a high school reunion.
The form should have text input fields for the person’s name and
