Advanced application of PHP file processing - file pointer
PHP can realize the positioning and query of the file pointer, thereby realizing the rapid query of the required information, file Pointer functions include rewind(), fseek(), feof() and ftell() functions.
In the previous article "Advanced Application of PHP File Processing—Remote File Access and Locking Files" we introduced the remote access of files and how to lock files. I didn’t read it. Friends, you can go and take a look. I won’t go into details here. Today we mainly talk about the functions in the file pointer!
1: rewind() function
This function sets the pointer of the file handle to the beginning of the file stream. The syntax format of this function is as follows :
bool rewind ( resource $handle )
Note:
If the file is opened with append ("a") mode, then any Data will always be appended to the end of the existing content of the file, no matter where the file pointer is!
2: fseek() function
The fseek() function implements the positioning of the file pointer. The syntax format of this function is as follows:
int fseek ( resource $handle , int $offset [, int $whence = SEEK_SET ] )
The handle parameter is the file to be opened.
offset is the pointer position or the offset relative to the whence parameter, which can be a negative value.
The value of whence includes the following three types:
1. SEEK_SET, the position is equal to offset bytes.
2. SEEK_CUR, the position is equal to the current position plus offset bytes.
3. SEEK_END, the position is equal to the end of the file plus offset bytes.
If the whence parameter is omitted, the system defaults to SEEK_SET.
3: feof() function
This function determines whether the file pointer is at the end of the file. The function syntax is as follows:
bool feof ( resource $handle )
If the pointer reaches the end of the file, return true, otherwise return false.
Four: ftell() function
ftell() function returns the position of the current pointer. The syntax format of this function is as follows:
int ftell ( resource $handle )
The following is to use the above four pointer functions to output the contents of the file. The sample code is as follows:
<?php
header("Content-Type:text/html; charset=utf-8");
$filename = "tm.txt"; //指定文件路徑及文件名
if(is_file($filename)){ //判斷文件是否存在
echo "文件總字節(jié)數(shù)：".filesize($filename)."<br>"; //輸出總字節(jié)數(shù)
$fopen = fopen($filename,"rb"); // 打開文件
echo "初始指針位置是：".ftell($fopen)."<br>"; //輸出指針位置
fseek($fopen,33); //制動指針
echo "使用fseek()函數(shù)后指針位置：".ftell($fopen)."<br>"; //輸出制動后的指針位置
echo "輸出當前指針后面的內(nèi)容：".fgets($fopen)."<br>"; //輸出從當前指針到行尾的內(nèi)容
if (feof($fopen)){ //判斷指針是否指向文件末尾
echo "當前指針指向文件末尾：".ftell($fopen)."<br>"; //如果指向了文件尾，則輸出指針位置
rewind($fopen); //使用rewind()函數(shù)
echo "使用 rewind()函數(shù)后指針的位置：".ftell($fopen)."<br>"; //查看使用rewind()函數(shù)后指針的位置
echo "輸出前33個字節(jié)的內(nèi)容：".fgets($fopen,33); //輸出前33個字節(jié)的內(nèi)容
fclose($fopen); //關(guān)閉文件
}else{
echo "文件不存在";
}
}
?>The output result is:
PHP The introduction of advanced applications of file processing is over here. Next, we will introduce PHP file upload. For details, please read "php file upload—Configuring the php.inn file and predefined variables $_FILES"!
The above is the detailed content of Advanced application of PHP file processing—file pointer. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
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
Why We Comment: A PHP Guide
Jul 15, 2025 am 02:48 AM
PHPhasthreecommentstyles://,#forsingle-lineand/.../formulti-line.Usecommentstoexplainwhycodeexists,notwhatitdoes.MarkTODO/FIXMEitemsanddisablecodetemporarilyduringdebugging.Avoidover-commentingsimplelogic.Writeconcise,grammaticallycorrectcommentsandu
How to Install PHP on Windows
Jul 15, 2025 am 02:46 AM
The key steps to install PHP on Windows include: 1. Download the appropriate PHP version and decompress it. It is recommended to use ThreadSafe version with Apache or NonThreadSafe version with Nginx; 2. Configure the php.ini file and rename php.ini-development or php.ini-production to php.ini; 3. Add the PHP path to the system environment variable Path for command line use; 4. Test whether PHP is installed successfully, execute php-v through the command line and run the built-in server to test the parsing capabilities; 5. If you use Apache, you need to configure P in httpd.conf
PHP Syntax: The Basics
Jul 15, 2025 am 02:46 AM
The basic syntax of PHP includes four key points: 1. The PHP tag must be ended, and the use of complete tags is recommended; 2. Echo and print are commonly used for output content, among which echo supports multiple parameters and is more efficient; 3. The annotation methods include //, # and //, to improve code readability; 4. Each statement must end with a semicolon, and spaces and line breaks do not affect execution but affect readability. Mastering these basic rules can help write clear and stable PHP code.
PHP 8 Installation Guide
Jul 16, 2025 am 03:41 AM
The steps to install PHP8 on Ubuntu are: 1. Update the software package list; 2. Install PHP8 and basic components; 3. Check the version to confirm that the installation is successful; 4. Install additional modules as needed. Windows users can download and decompress the ZIP package, then modify the configuration file, enable extensions, and add the path to environment variables. macOS users recommend using Homebrew to install, and perform steps such as adding tap, installing PHP8, setting the default version and verifying the version. Although the installation methods are different under different systems, the process is clear, so you can choose the right method according to the purpose.
Your First PHP Script: A Practical Introduction
Jul 16, 2025 am 03:42 AM
How to start writing your first PHP script? First, set up the local development environment, install XAMPP/MAMP/LAMP, and use a text editor to understand the server's running principle. Secondly, create a file called hello.php, enter the basic code and run the test. Third, learn to use PHP and HTML to achieve dynamic content output. Finally, pay attention to common errors such as missing semicolons, citation issues, and file extension errors, and enable error reports for debugging.
What is PHP and What is it Used For?
Jul 16, 2025 am 03:45 AM
PHPisaserver-sidescriptinglanguageusedforwebdevelopment,especiallyfordynamicwebsitesandCMSplatformslikeWordPress.Itrunsontheserver,processesdata,interactswithdatabases,andsendsHTMLtobrowsers.Commonusesincludeuserauthentication,e-commerceplatforms,for
python if else example
Jul 15, 2025 am 02:55 AM
The key to writing Python's ifelse statements is to understand the logical structure and details. 1. The infrastructure is to execute a piece of code if conditions are established, otherwise the else part is executed, else is optional; 2. Multi-condition judgment is implemented with elif, and it is executed sequentially and stopped once it is met; 3. Nested if is used for further subdivision judgment, it is recommended not to exceed two layers; 4. A ternary expression can be used to replace simple ifelse in a simple scenario. Only by paying attention to indentation, conditional order and logical integrity can we write clear and stable judgment codes.
How Do You Handle File Operations (Reading/Writing) in PHP?
Jul 16, 2025 am 03:48 AM
TohandlefileoperationsinPHP,useappropriatefunctionsandmodes.1.Toreadafile,usefile_get_contents()forsmallfilesorfgets()inaloopforline-by-lineprocessing.2.Towritetoafile,usefile_put_contents()forsimplewritesorappendingwiththeFILE_APPENDflag,orfwrite()w
