Php i basic chapter 4

PHP Workshop 1
File Handling with PHP

PHP Workshop 2
Files and PHP
• File Handling
– Data Storage
• Though slower than a database
– Manipulating uploaded files
• From forms
– Creating Files for download

PHP Workshop 3
Open/Close a File
• A file is opened with fopen() as a “stream”,
and PHP returns a ‘handle’ to the file that
can be used to reference the open file in
other functions.
• Each file is opened in a particular mode.
• A file is closed with fclose() or when your
script ends.

PHP Workshop 4
File Open Modes
‘r’ Open for reading only. Start at beginning of
file.
‘r+’ Open for reading and writing. Start at
beginning of file.
‘w’ Open for writing only. Remove all previous
content, if file doesn’t exist, create it.
‘a’ Open writing, but start at END of current
content.
‘a+’ Open for reading and writing, start at END
and create file if necessary.

PHP Workshop 5
File Open/Close Example
<?php
// open file to read
$toread = fopen(‘some/file.ext’,’r’);
// open (possibly new) file to write
$towrite = fopen(‘some/file.ext’,’w’);
// close both files
fclose($toread);
fclose($towrite);
?>

PHP Workshop 6
Now what..?
• If you open a file to read, you can use
more in-built PHP functions to read data..
• If you open the file to write, you can use
more in-built PHP functions to write..

PHP Workshop 7
Reading Data
• There are two main functions to read data:
• fgets($handle,$bytes)
– Reads up to $bytes of data, stops at newline
or end of file (EOF)
• fread($handle,$bytes)
– Reads up to $bytes of data, stops at EOF.

PHP Workshop 8
Reading Data
• We need to be aware of the End Of File
(EOF) point..
• feof($handle)
– Whether the file has reached the EOF point.
Returns true if have reached EOF.

PHP Workshop 9
Data Reading Example
$handle = fopen('people.txt', 'r');
while (!feof($handle)) {
echo fgets($handle, 1024);
echo ' ';
}
fclose($handle);

PHP Workshop 10
echo ' ';
}
fclose($handle);
Open the file and assign the resource to $handle

PHP Workshop 11
echo ' ';
}
fclose($handle);
While NOT at the end of the file, pointed
to by $handle,
get and echo the data line by line
echo ' ';
}

PHP Workshop 12
echo ' ';
}
fclose($handle);
Close the file
fclose($handle);

PHP Workshop 13
File Open shortcuts..
• There are two ‘shortcut’ functions that don’t
require a file to be opened:
• $lines = file($filename)
– Reads entire file into an array with each line a
separate entry in the array.
• $str = file_get_contents($filename)
– Reads entire file into a single string.

PHP Workshop 14
Writing Data
• To write data to a file use:
• fwrite($handle,$data)
– Write $data to the file.

PHP Workshop 15
Data Writing Example
$handle = fopen('people.txt', 'a');
fwrite($handle, “nFred:Male”);
fclose($handle);

PHP Workshop 16
Data Writing Example
fwrite($handle, 'nFred:Male');
fclose($handle);
Open file to append data (mode 'a')
fwrite($handle, “nFred:Male”);
Write new data (with line
break after previous data)

PHP Workshop 17
Other File Operations
• Delete file
– unlink('filename');
• Rename (file or directory)
– rename('old name', 'new name');
• Copy file
– copy('source', 'destination');
• And many, many more!
– www.php.net/manual/en/ref.filesystem.php

PHP Workshop 18
Dealing With Directories
• Open a directory
– $handle = opendir('dirname');
• $handle 'points' to the directory
• Read contents of directory
– readdir($handle)
• Returns name of next file in directory
• Files are sorted as on filesystem
• Close a directory
– closedir($handle)
• Closes directory 'stream'

PHP Workshop 19
Directory Example
$handle = opendir('./');
while(false !== ($file=readdir($handle)))
{
echo "$file ";
}
closedir($handle);

PHP Workshop 20
Directory Example
{
echo "$file ";
}
closedir($handle);
Open current directory

PHP Workshop 21
Directory Example
{
echo "$file ";
}
closedir($handle);
Whilst readdir() returns a name, loop
through directory contents, echoing
results
{
echo "$file ";
}

PHP Workshop 22
Directory Example
{
echo "$file ";
}
closedir($handle);
Close the directory stream
closedir($handle);

PHP Workshop 23
Other Directory Operations
• Get current directory
– getcwd()
• Change Directory
– chdir('dirname');
• Create directory
– mkdir('dirname');
• Delete directory (MUST be empty)
– rmdir('dirname');
• And more!
– www.php.net/manual/en/ref.dir.php

PHP Workshop 24
Review
• Can open and close files.
• Can read a file line by line or all at one go.
• Can write to files.
• Can open and cycle through the files in a
directory.

PHP Workshop 25
Review all
• Create a File
$my_file = 'file.txt';
$handle = fopen($my_file, 'w') or
die('Cannot open file: '.$my_file);
//implicitly creates file

PHP Workshop 26
Review all
• Open a File
die('Cannot open file: '.$my_file); //open
file for writing ('w','r','a')...

PHP Workshop 27
Review all
• Read a File
$handle = fopen($my_file, 'r');
$data = fread($handle,filesize($my_file));

PHP Workshop 28
Review all
• Write to a File
$data = 'This is the data';
fwrite($handle, $data);

PHP Workshop 29
Review all
• Append to a File
$handle = fopen($my_file, 'a') or die('Cannot
open file: '.$my_file);
$data = 'New data line 1';
fwrite($handle, $data);
$new_data = "n".'New data line 2';
fwrite($handle, $new_data);

PHP Workshop 30
Review all
• Close a File
//write some data here
fclose($handle);

PHP Workshop 31
Review all
• Delete a File
unlink($my_file);

Php i basic chapter 4

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Php i basic chapter 4