Thông tin tài liệu
The ftell() Function—Finding the Current Position in a File
If you have read some data from a file and want to keep track of where you were in the file when you stopped reading,
the ftell() function will return the current byte position, the number of bytes from the beginning of the file, and
where the next read operation will start. This can be used in conjunction with the seek() function to return to the
correct position in the file. (If you are using text mode, the carriage return and linefeed translation will be part of the
byte count.)
Format
int ftell ( resource handle )
%
Example:
$filehandle("myfile", "r"); $contents=fgets($filehandle, 1024); echo ftell(
$filehandle); // Current read postion in bytes, //
starting at byte 1024
Example 11.9.
4)3#%!"#$c%
<html><head><title>The ftell() Function</title></head>
<body bgcolor="lavender">
<h3>Marking a Position in a File</h3>
<pre>
<?php
//$filename="c:/wamp/www/exemples/data.file";
$filename="$_SERVER[DOCUMENT_ROOT]/exemples/data.file";
if (!file_exists($filename)){
print "No such file or directory";
exit();
}
1 $fh=fopen($filename,"r");
2 $substring="eastern";
while( !feof($fh)){
$line_of_text=fgets($fh);
echo "$line_of_text";
3 if(substr_count($line_of_text, $substring)) {
4 $bytes=ftell($fh);
}
}
if (! isset($bytes)){
echo "$substring not found<br />";
exit();
}
5 fseek($fh, $bytes, SEEK_SET);
echo "<hr />";
echo "<b>Start reading again from byte position $bytes</b>
<br />";
while( !feof($fh)){
6 $line_of_text=fgets($fh);
echo "$line_of_text";
}
fclose($fh);
?> </pre> </body> </html>
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Explanation
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R=#%7"1'&%&"5#%&="'%7<*(&")*%1#&<1*'%D%)1%5)1#.%&=#%*#;&%8"*#%$"88%T#%#*#3-
@
R=#%ftell()%7<*(&")*%$"88%1#&<1*%&=#%T0&#%/)'"&")*%)7%$=#1#%&=#%*#;&%1#23%
)/#12&")*%$"88%&2N#%/82(#-%R=#%8"*#%()*&2"*"*>%"eastern"%=2'%281#230%T##*%
1#23-%R=#%T0&#%/)'"&")*%"'%&=#%*<5T#1%)7%(=212('%71)5%&=#%T#>"**"*>%)7%&=#%
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&=#%/)'"&")*%1#&<1*#3%71)5%ftell().%T0&#%CiD.%"*%&="'%#;25/8#-%M##%`"><1#%
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$=#1#%&=#%'<T'&1"*>%"eastern"%$2'%7)<*3-
Figure 11.10. Marking a position with ftell(). Output from Example 11.9.
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11.2.6. Opening a URL for Reading
You can open files with FTP or HTTP with the fopen() function. (Note: If opening the URL fails, check if the
allow_url_fopen directive in the php.ini file is disabled.)
Format
resource fopen ( string filename, string mode [, bool
use_include_path [, resource zcontext]] )
%
Example:
$filehandle=fopen('http://www.site.com/');
$filehandle=fopen('ftp://username:password@ftp.wherever.com/pub/index' , 'r');
Example 11.10.
<html><head><title>Open a File</title></head>
<body bgcolor="lavender">
<?php
1 $filename="http://www.ellieq.com/";
2 $fh=fopen("$filename", "r");
3 while( !feof($fh) ){
4 $contents=htmlspecialchars(fgets($fh, 1024));
print "<pre>$contents</pre>";
}
fclose($fh);
?>
</body>
</html>
Explanation
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R=#%fgets()%7<*(&")*%1#23'%DAC@%T0&#'%2&%2%&"5#%71)5%&=#%/2>#-%R=#%
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'=)$*%"*%`"><1#%DD-DD%"'%&=#%2(&<28%')<1(#%/2>#%+!"#$%M)<1(#,%&=2&%$2'%<'#3%&)%(1#2&#%
&=#%/2>#-
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Figure 11.11. Viewing the contents of a Web page opened as a URL.
%
11.2.7. Reading from Files Without a Filehandle
PHP provides functions that allow you to read the contents of a file without first opening a filehandle.
The file_get_contents() Function—Reading the Whole File into a String
An easy way to read the contents of an entire file is with the file_get_contents() function. You do not even
need to get a filehandle, just pass the name of the file to the function and it will get the contents of the whole file and
store it in a string. You can also start reading from a specified offset in the file and specify how many bytes you want to
read. The file_get_contents() function will return FALSE, if it fails. The PHP manual suggests this as the most
efficient way to read a file into a string.
Format
string file_get_contents ( string filename [, bool use_include_path [,
resource context [, int offset [, int maxlen]]]] )
%
Example:
$contents=file_get_contents("datafile.txt");
The file() Function—Reading the Whole File into an Array
Without using a filehandle, you can read an entire file into an array with PHP’s file() function. The filename can be
a full path, relative path, or even a URL (if each element of the array corresponds to a line in the file, with the newline
still attached. The function returns FALSE if it fails. If you do not want the end-of-line character at the end of each of
the array elements, use the rtrim() function, described in Chapter 6, “Strings.”
[5]
This function is identical to
file_get_contents(), except that it returns the file in an array.
[5]
If PHP does not recognize the line endings (Macintosh), see the php.ini file to enable the
auto_detect_line_endings runtime configuration option.
Format
array file ( string filename [, int use_include_path [, resource
context]] )
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Example 11.11.
<html><head><title>Parsing Lines</title></head>
<body bgcolor="lightgreen">
<font face=verdana" size="+2">
<?php
if( ! isset($_POST['submit'])){
1 show_form();
}
else{
2 process_file();
}
3 function show_form(){
?>
<h2>Exploding and Imploding</h2>
<form method=POST
action="<?php echo $_SERVER['PHP_SELF'];?>">
<table cellspacing="0" cellpadding="2">
<tr>
<b> Select a first name from the file.</b>
<td><input type="text" size=30
name="first_name" </td>
</tr>
<tr>
<td> </td>
</tr>
<tr>
<td><input type="submit" name="submit"
</tr><br />
</table>
</form>
<?php
}
4 function process_file(){
$filename="$_SERVER[DOCUMENT_ROOT]/ /mydir/datebook";
5 $lines = file($filename); // Lines of file stored in an
array
6 $first_name=trim($_POST['first_name']);
7 foreach ($lines as $line_value) {
8 $fields=explode(":", $line_value);
9 $fullname=explode(" ", $fields[0]);
$phone=$fields[1];
$address=$fields[2];
$birthday=$fields[3];
$salary=$fields[4];
10 if( strcasecmp($fullname[0],$first_name) == 0 ){
11 $birth=explode("/",$birthday);
12 $newstring=implode("<br
/>",array($fields[0],$phone,
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$address,"19".$birth[2], '$'.number_format($salary,2)));
13 echo "$newstring<br />";
14 $count++;
echo "<hr />";
}
}
15 if($count==0){
echo "$first_name is not in the file.<br />";
}
}
?>
</b>
</font>
</body>
</html>
Explanation
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#;#(<-
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Figure 11.12. Using the file() function, creating line numbers.
Using explode() and implode()
After you have read in a line from a file or you get input from a file, you might want to break the lines into individual
fields or create a string from an array of input items. This is where the array functions explode() and implode()
can be useful, array functions discussed in Chapter 8, “Arrays.”
Example 11.12 demonstrates how to use these functions. This example uses the text file called datebook.
[6]
Below are
two lines from this file. Notice that the fields are separated by colons.
[6]
The datebook file can be found on the CD in the back of this book.
Steve Blenheim:238-923-7366:95 Latham Lane, Easton, PA 83755:11/12/56:20300
Betty Boop:245-836-8357:635 Cutesy Lane, Hollywood, CA 91464:6/23/23:14500
%
Example 11.12.
4)3#%!"#$c%
<html><head><title>Parsing Lines</title></head>
<body bgcolor="lightgreen">
<font face=verdana" size="+2">
<?php
if( ! isset($_POST['submit'])){
1 show_form();
}
else{
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2 process_file();
}
3 function show_form(){
?>
<h2>Exploding and Imploding</h2>
<form method=POST
action="<?php echo $_SERVER['PHP_SELF'];?>">
<table cellspacing="0" cellpadding="2">
<tr>
<b> Select a first name from the file.</b>
<td><input type="text" size=30
name="first_name" </td>
</tr>
<tr>
<td> </td>
</tr>
<tr>
<td><input type="submit" name="submit"
</tr><br />
</table>
</form>
<?php
}
4 function process_file(){
$filename="$_SERVER[DOCUMENT_ROOT]/ /mydir/datebook";
5 $lines = file($filename); // Lines of file stored in an
array
6 $first_name=trim($_POST['first_name']);
7 foreach ($lines as $line_value) {
8 $fields=explode(":", $line_value);
9 $fullname=explode(" ", $fields[0]);
$phone=$fields[1];
$address=$fields[2];
$birthday=$fields[3];
$salary=$fields[4];
10 if( strcasecmp($fullname[0],$first_name) == 0 ){
11 $birth=explode("/",$birthday);
12 $newstring=implode("<br
/>",array($fields[0],$phone,
$address,"19".$birth[2], '$'.number_format($salary,2)));
13 echo "$newstring<br />";
14 $count++;
echo "<hr />";
}
}
15 if($count==0){
echo "$first_name is not in the file.<br />";
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}
}
?>
</b>
</font>
</body>
</html>
Explanation
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Figure 11.13. The HTML form.
%
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[...]... arguments: the filehandle returned by fopen() and an optional length argument, how many bytes to write to the file If it fails, fwrite() returns FALSE The file_put_contents() Function The file_put_contents() also writes a string to a file and returns the number of bytes written, but does not require a filehandle Otherwise it is the same as fwrite() and fputs() Format int fwrite ( filehandle, string, [... manageable for designers and programmers, but easier to navigate and debug This section focuses on how to include simple files to help manage content (There are many templating solutions available for PHP today easily found on the Web See http://smarty .php. net to find about Smarty, a template engine designed for PHP. ) To include files in your PHP program, the PHP include() and require() functions are... arial font, centered and vertically aligned at the top of the page Figure 11.24 The page header Example 11.27 Code View: (The main page: page .php) < ?php 1 2 $page_name = $_REQUEST['name']; /*http://localhost/exemples/page .php? name=about_us */ // Get the body of the page mysql_ connect("localhost","root","") or die (mysql_ error()); mysql_ select_db("test") or die (mysql_ error()); $sql =... instant feedback, and less travelling back and forth between the browser and server, but to ensure that the data has been verified, PHP can recheck it Once the user has filled out a form and submitted it, PHP can check to see if all the boxes have been filled out correctly, and if not, the user is told to reenter the data before the form data is processed With the power provided by regular expressions,... as its argument and returns TRUE if the filename exists and is readable If the PHP script is being executed by the server, the server’s permissions (usually limited) determine whether or not the PHP program can read from the file, and if it is being executed at the shell prompt, the permissions of the user running the script are the deciding factor Normally, the file should be readable by others Format... though the MySQL database system is not discussed until Chapter 13, “Introduction to MySQL, ” we use it here to provide a more real-‐world example All you really need to understand is that the the PHP script makes a connection to a database and fetches data from it that will be displayed in the browser In this line, the PHP mysql_ connect()... text and binary files for reading, writing, and appending from within a PHP script, how to deal with permissions and ownership, upload files, and navigate directories The last part of the chapter discussed content management using external files 11.5.1 What You Should Know Now that you have finished this chapter you should be able to answer the following questions: 1 What is a filehandle and how... writable? 10 What is meant by “uploading” a file? What encoding type is used by the browser for file uploads? 11 How do you copy and remove files? 12 How do you open a directory in a PHP script and list its contents? 13 How do you manage files with include() and require()? 11.5.2 What’s Next? In Chapter 12, “Regular Expressions and Pattern Matching,” we... /^[a-zA-Z][\w\.\-]+[a-zA-Z0-9]@([a-zA-Z0-9][a-zA-Z0-9\-]*\.)+[a-zA-Z]{2,4}$/ is called a regular expression and might look like jibberish, but by the time you finish this chapter, you will understand what all these symbols mean and how to use them We will break the expression into very small units, and when all of the pieces have been explained, we will use it to validate an HTML form Let’s start by defining a regular expression and what it is used for When a user fills... series of bytes If the file contents look weird when it is opened or you have a lot broken images, use the "b" mode $handle = fopen("/home/marko/file.txt", "wb"); $handle = fopen("http://www.ellieq.com/", "w"); $handle = fopen("ftp://user:password@ellieq.com/myfile.txt", "a"); The fwrite() and fputs() Functions The fwrite() function writes a string text to a file and returns the number of bytes written . the carriage return and linefeed translation will be part of the
byte count.)
Format
int ftell ( resource handle )
%
Example:
$filehandle("myfile",. "r"); $contents=fgets($filehandle, 1024); echo ftell(
$filehandle); // Current read postion in bytes, //
starting at byte 1024
Example 11.9.
4)3#%!"#$c%
<html><head><title>The
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