PHP File HandlingManipulating files is a basic necessity for serious programmers and PHP gives you a great deal of tools for creating, uploading, and editing files. Remember: When you are manipulating files you must be very careful because you can do a lot of damage if you do something wrong. Common errors include editing the wrong file, filling a hard-drive with garbage data, and accidentally deleting a file's contents. It is our hope that you will be able to avoid these and other slipups after reading this tutorial. However, we know that there are so many places where code can take a wrong turn, so we urge you to take extra care when dealing with files in PHP. The fopen() function is used to open files in PHP. The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened: Code: <html>
<body>
<?php
$file=fopen("welcome.txt","r");
?>
</body>
</html> The file may be opened in one of the following modes: | Modes | Description |
|---|
| r | Read only. Starts at the beginning of the file | | r+ | Read/Write. Starts at the beginning of the file | | w | Write only. Opens and clears the contents of file; or creates a new file if it doesn't exist | | w+ | Read/Write. Opens and clears the contents of file; or creates a new file if it doesn't exist | | a | Append. Opens and writes to the end of the file or creates a new file if it doesn't exist | | a+ | Read/Append. Preserves file content by writing to the end of the file | | x | Write only. Creates a new file. Returns FALSE and an error if file already exists | | x+ | Read/Write. Creates a new file. Returns FALSE and an error if file already exists |
Note: If the fopen() function is unable to open the specified file, it returns 0 (false). Example: The following example generates a message if the fopen() function is unable to open the specified file: Code: <html>
<body>
<?php
$file=fopen("welcome.txt","r") or exit("Unable to open file!");
?>
</body>
</html> The fclose() function is used to close an open file: Code: <?php
$file = fopen("test.txt","r");
//some code to be executed
fclose($file);
?> The feof() function checks if the "end-of-file" (EOF) has been reached.
The feof() function is useful for looping through data of unknown length. Note: You cannot read from files opened in w, a, and x mode! Code: if (feof($file)) echo "End of file"; Reading a File Line by Line
The fgets() function is used to read a single line from a file. Note: After a call to this function the file pointer has moved to the next line. Example: The example below reads a file line by line, until the end of file is reached: Code: <?php
$file = fopen("welcome.txt", "r") or exit("Unable to open file!");
//Output a line of the file until the end is reached
while(!feof($file))
{
echo fgets($file). "<br />";
}
fclose($file);
?> Reading a File Character by Character
The fgetc() function is used to read a single character from a file. Note: After a call to this function the file pointer moves to the next character. Example: The example below reads a file character by character, until the end of file is reached: Code: <?php
$file=fopen("welcome.txt","r") or exit("Unable to open file!");
while (!feof($file))
{
echo fgetc($file);
}
fclose($file);
?> For a complete reference , please visit: www.php.net |
File