Detailed explanation and examples of PHP file reading and writing methods

Detailed explanation and examples of PHP file reading and writing methods

1. Overview
In the PHP development process, file reading and writing are very important. Commonly used operations. File reading helps us get the file content, while file writing is used to write the content to the file. This article will introduce in detail the file reading and writing methods in PHP and provide corresponding code examples.

2. File reading method

1. fopen() function
   fopen() function is the most basic file reading function in PHP, used to open a file and return A resource stream. It accepts two parameters: file name and opening mode. The open mode can be "r" (read-only), "w" (write, create if file does not exist), "a" (append, create if file does not exist), "x" (write-only, if file already exists) then returns false), "b" (binary mode), etc.

Code example:

$file = fopen("file.txt", "r");
if ($file) {
    while (($line = fgets($file)) !== false) {
        echo $line;
    }
    fclose($file);
}

2. file_get_contents() function
   The file_get_contents() function is used to read the entire file into a string. This function is very convenient, you only need to pass in the file name as a parameter.

Code example:

$fileContent = file_get_contents("file.txt");
echo $fileContent;

3. fread() function
   The fread() function is used in conjunction with the fopen() function to read content of a specified length. It accepts two parameters: file resource and length.

Code example:

$file = fopen("file.txt", "r");
if ($file) {
    $content = fread($file, filesize("file.txt"));
    echo $content;
    fclose($file);
}

3. File writing method

1. fopen() function
   fopen() function can also be used for files To write, just set the open mode to "w" or "a".

Code example:

$file = fopen("file.txt", "w");
if ($file) {
    fwrite($file, "Hello, World!");
    fclose($file);
}

2. file_put_contents() function
   file_put_contents() function can write the contents into a file. It is a very convenient function without Open the file first and then write.

Code example:

file_put_contents("file.txt", "Hello, World!");

3. fwrite() function
   The fwrite() function needs to first open the file through the fopen() function and use the opened file resource as The first parameter is passed in.

Code example:

$file = fopen("file.txt", "w");
if ($file) {
    fwrite($file, "Hello, World!");
    fclose($file);
}

4. Summary
Through the above introduction, we have learned about the reading and writing methods of files in PHP. Whether using the fopen() function, file_get_contents() function, fread() function, or using the fopen() function, file_put_contents() function, or fwrite() function, we can all read and write files. Select the appropriate method according to actual needs to handle file operations more efficiently.

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