File handling: PHP

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File handling in PHP is the process of reading from and writing to files on a filesystem. PHP provides several built-in functions for working with files:

  1. Opening files: The fopen() function is used to open a file for reading or writing. It takes two parameters: the name of the file to open, and the mode in which to open it. For example, to open a file named ‘data.txt’ for reading, you can use the following code:

    bash
    $handle = fopen('data.txt', 'r');

    This code opens the file in read-only mode, and returns a file handle that can be used to read data from the file.

  2. Reading files: Once a file is open, you can use the fgets() function to read a line of text from the file, or the fread() function to read a specified number of bytes. For example, to read the entire contents of a file into a string, you can use the following code:

    bash
    $handle = fopen('data.txt', 'r');
$contents = fread($handle, filesize('data.txt'));
fclose($handle);

    This code reads the entire contents of the file into a string variable, and then closes the file handle using the fclose() function.

  3. Writing files: To write data to a file, you can use the fwrite() function, which takes two parameters: the file handle, and the data to write. For example, to write a line of text to a file named ‘output.txt’, you can use the following code:

    bash
    $handle = fopen('output.txt', 'w');
fwrite($handle, 'Hello, world!');
fclose($handle);

    This code opens the file in write-only mode, writes the text ‘Hello, world!’ to the file, and then closes the file handle.

  4. Closing files: Once you are finished reading from or writing to a file, you should close the file handle using the fclose() function. This releases any system resources that were used to access the file. For example:

    perl
    $handle = fopen('data.txt', 'r');
// read data from file
fclose($handle);

    This code opens a file for reading, performs some operations on the file, and then closes the file handle.

PHP also provides several other functions for working with files, such as file_get_contents() and file_put_contents() for reading and writing entire files at once, and fseek() and ftell() for positioning within a file. Additionally, PHP provides functions for working with directories, such as opendir(), readdir(), and closedir(), for reading the contents of a directory.

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