Knowledge about PHP file opening/reading/reading

Opening and reading php files is very important for php. This article will explain the relevant knowledge of opening and reading php files in detail.

PHP Open File - fopen()

A better way to open a file is through the fopen() function. This function gives you more options than the readfile() function.

In the course we will use the text file "webdictionary.txt":

AJAX = Asynchronous JavaScript and XML
CSS = Cascading Style Sheets
HTML = Hyper Text Markup Language
PHP = PHP Hypertext Preprocessor
SQL = Structured Query Language
SVG = Scalable Vector Graphics
XML = EXtensible Markup Language

fopen() The first parameter contains the name of the file to be opened, and the second parameter specifies the mode for opening the file. If the fopen() function fails to open the specified file, the following example will generate a message:

Example

<?php
$myfile = fopen("webdictionary.txt", "r") or die("Unable to open file!");
echo fread($myfile,filesize("webdictionary.txt"));
fclose($myfile);
?>

Tip: We will learn about the fread() and fclose() functions next.

PHP Read file - fread()

fread() function reads an open file.

The first parameter of fread() contains the file name of the file to be read, and the second parameter specifies the maximum number of bytes to be read.

The following PHP code reads the "webdictionary.txt" file to the end:

fread($myfile,filesize("webdictionary.txt"));

PHP Close File - fclose()

fclose() function is used to close an open file.

Note: It is a good programming habit to close all files after using them. You don't want to open files that use up your server resources.

fclose() requires the name of the file to be closed (or a variable holding the file name):

<?php
$myfile = fopen("webdictionary.txt", "r");// some code to be executed....fclose($myfile);
?>

PHP reads a single line file - fgets()

fgets() Function is used to read a single line from a file.

The following example outputs the first line of the "webdictionary.txt" file:

Example

<?php
$myfile = fopen("webdictionary.txt", "r") or die("Unable to open file!");
echo fgets($myfile);
fclose($myfile);
?>

Note: After calling the fgets() function, the file pointer will move to the next line.

PHP Check End-Of-File - feof()

feof() function checks whether "end-of-file" (EOF) has been reached.

feof() is useful for iterating over data of unknown length.

The following example reads the "webdictionary.txt" file line by line until end-of-file:

Example

<?php
$myfile = fopen("webdictionary.txt", "r") or die("Unable to open file!");// 输出单行直到 end-of-filewhile(!feof($myfile)) {
  echo fgets($myfile) . "<br>";
}
fclose($myfile);
?>

PHP reads a single character - fgetc()

fgetc() function is used to read a single character from a file.

The following example reads the "webdictionary.txt" file character by character until end-of-file:

Example

<?php
$myfile = fopen("webdictionary.txt", "r") or die("Unable to open file!");// 输出单字符直到 end-of-filewhile(!feof($myfile)) {
  echo fgetc($myfile);
}
fclose($myfile);
?>

Comments: After calling the fgetc() function, The file pointer moves to the next character.

This article explains the knowledge about opening and reading PHP files. For more learning materials, please pay attention to the PHP Chinese website.

Related recommendations:

Explanation on PHP Include files

Instructions on the use of PHP EOF (heredoc)

About PHP loops - Detailed explanation of For loop

The above is the detailed content of Knowledge about PHP file opening/reading/reading. For more information, please follow other related articles on the PHP Chinese website!