The file_exists() function in PHP is used to check whether a file or directory exists. It returns true if the file or directory exists, and false otherwise.

Syntax:

file_exists(string $filename): bool

• $filename: The path to the file or directory.

Example 1: Checking if a file exists

<?php
$file = 'example.txt';

if (file_exists($file)) {
    echo "The file '$file' exists.";
} else {
    echo "The file '$file' does not exist.";
}
?>

Output:

The file 'example.txt' exists.

Example 2: Checking if a directory exists

<?php
$directory = 'images/';

if (file_exists($directory)) {
    echo "The directory '$directory' exists.";
} else {
    echo "The directory '$directory' does not exist.";
}
?>

Output:

The directory 'images/' exists.

Example 3: Using with a non-existent file

<?php
$file = 'nonexistent.txt';

if (file_exists($file)) {
    echo "The file '$file' exists.";
} else {
    echo "The file '$file' does not exist.";
}
?>

Output:

The file 'nonexistent.txt' does not exist.

Important Notes:

• file_exists() can check for both files and directories.
• It returns false for symlinks pointing to a non-existent target.
• Ensure that the script has the correct file permissions to check the file or directory existence.

This function is commonly used for validating the existence of a file before performing further operations like reading or writing to it.