Backend Development
PHP Tutorial
Detailed discussion of directory and file operations in php_PHP tutorial
Detailed discussion of directory and file operations in php_PHP tutorial
1. Introduction
In any computer device, files are necessary objects. In web programming, file operations have always been a headache for web programmers. However, file operations are very difficult in cms systems. It is necessary and very useful. We often encounter operations such as generating file directories, editing files (folders), etc. Now I will make a detailed summary of these functions in PHP and demonstrate how to use them with examples. Regarding the corresponding functions in detail, Please refer to the PHP manual. Here we only summarize the key points and points that need attention. (This is not found in the PHP manual.)
2. Directory operation
The first one introduced is a function that reads from the directory, opendir (), readdir(), closedir(), when used, open the file handle first, and then list it iteratively:
$base_dir = "filelist/";
$fso = opendir($base_dir);
echo $base_dir."
" ;
while($flist=readdir($fso)){
echo $flist."
" ;
}
closedir($fso)
?>
This is a program that returns the files and directories under the file directory (0 files will return false).
Sometimes you need to know the directory information, you can use dirname($path) and basename($path), respectively return the directory part and file name part of the path. You can use disk_free_space($path) to return the free space.
Creation command:
mkdir($path,0777)
, 0777 is the permission code, which can be set by the umask() function under non-window conditions.
rmdir($path)
will delete the file with the path in $path.
dir -- directory class also operates the file directory. The important class has three methods, read, rewind, and close. This is a pseudo-object-oriented class. It first uses a file handle to open and then reads it using a pointer. See the PHP manual here:
$d = dir("/etc/php5");
echo "Handle: " . $d->handle . "n";
echo "Path: " . $d->path . "n";
while (false !== ($ entry = $d->read())) {
echo $entry."n";
}
$d->close();
?>
Output:
Handle: Resource id #2
Path: /etc/php5
.
..
apache
cgi
cli
file The attributes are also very important. File attributes include creation time, last modification time, owner, file group, type, size, etc.
Let’s focus on file operations below.
3. File operations
● Reading files
First, check whether a file can be read (permission issue), or whether it exists. We can use the is_readable function to obtain the information.:
$file = 'dirlist.php';
if (is_readable($file) == false) {
die('file Does not exist or cannot be read');
} else {
echo 'exists';
}
?>
The function to determine the existence of a file also includes file_exists (Demonstrated below), but this is obviously not as comprehensive as is_readable. When a file exists, you can use
$file = "filelist.php";
if (file_exists($file) == false) {
die('File does not exist');
}
$data = file_get_contents($file);
echo htmlentities($data);
?>
But the file_get_contents function is not supported on lower versions, you can create it first A handle to the file, and then use the pointer to read the entire file:
$fso = fopen($cacheFile, 'r');
$data = fread($fso, filesize($cacheFile));
fclose ($fso);
There is another way to read binary files:
$data = implode('', file($file));
● Write file
and read The file method is the same, first check if it can be written:
$file = 'dirlist.php';
if (is_writable($file) == false) {
die("I am a chicken, I can't" ; As follows:
$file = 'dirlist.php';
if (is_writable($file) == false) {
The file_put_contents function is a newly introduced function in php5 (if you don’t know it exists, use the function_exists function to determine it first). Lower versions of PHP cannot be used. You can use the following method:
$f = fopen($file, 'w ');
fwrite($f, $data);
fclose($f);
Replace it.
Sometimes you need to lock when writing a file, then write:
The code is as follows:
function cache_page($pageurl,$pagedata){
if(!$fso=fopen($pageurl ,'w')){
$this->warns('Unable to open cache file.');//trigger_error
$this->warns('Unable to write cache file.');//trigger_error
return false;
}
flock($fso,LOCK_UN);//Release the lock
fclose($fso);
return true;
}
● Copy and delete files
It is very easy to delete files in php. It is simple to use the unlink function:
Copy code
The code is as follows:
$file = 'dirlist.php';
$result = @unlink ($file);
That's it.
Copying files is also easy:
Copy code
The code is as follows:
$file = 'yang.txt';
$newfile = 'ji.txt'; # The parent folder of this file must be writable
?>
You can use the rename() function to rename a folder. Other operations can be achieved by combining these functions.
● Get file attributes
Let me tell you a few Common functions:
Get the latest modification time:
Copy code
The code is as follows:
$file = 'test.txt';
echo date('r', filemtime($file));
(non-window system), ileperms() obtains the file permissions,
Copy code
The code is as follows:
$file = 'dirlist.php';
$perms = substr(sprintf('%o', fileperms($file)), -4);
echo $perms;
?>
filesize() returns the number of bytes of the file size:
// The output is similar: somefile.txt: 1024 bytes
$filename = 'somefile.txt';
echo $filename . ': ' . filesize($filename) . ' bytes';
?>
$file = 'dirlist.php';
$perms = stat($file ; I briefly summarized several file operations above. If you are proficient in the functions listed above, there will be no big problems when operating. The functions of PHP file operations change relatively quickly and are now very powerful. The file part It is also a very important part of learning php, I hope you will not ignore it.
http://www.bkjia.com/PHPjc/318069.html
www.bkjia.com
true
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
CakePHP Project Configuration
Sep 10, 2024 pm 05:25 PM
In this chapter, we will understand the Environment Variables, General Configuration, Database Configuration and Email Configuration in CakePHP.
PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian
Dec 24, 2024 pm 04:42 PM
PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati
CakePHP Date and Time
Sep 10, 2024 pm 05:27 PM
To work with date and time in cakephp4, we are going to make use of the available FrozenTime class.
CakePHP File upload
Sep 10, 2024 pm 05:27 PM
To work on file upload we are going to use the form helper. Here, is an example for file upload.
CakePHP Routing
Sep 10, 2024 pm 05:25 PM
In this chapter, we are going to learn the following topics related to routing ?
Discuss CakePHP
Sep 10, 2024 pm 05:28 PM
CakePHP is an open-source framework for PHP. It is intended to make developing, deploying and maintaining applications much easier. CakePHP is based on a MVC-like architecture that is both powerful and easy to grasp. Models, Views, and Controllers gu
CakePHP Creating Validators
Sep 10, 2024 pm 05:26 PM
Validator can be created by adding the following two lines in the controller.
How To Set Up Visual Studio Code (VS Code) for PHP Development
Dec 20, 2024 am 11:31 AM
Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c
