PHP function introduction—file_exists(): Check whether a file or directory exists

PHP function introduction—file_exists(): Check whether a file or directory exists

Introduction:
In PHP programming, we often need to check whether a file or directory exists in order to perform corresponding processing. PHP's file_exists() function is a function used to check whether the specified file or directory exists.

Syntax:
bool file_exists (string $filename)

Parameters:

• filename: The path of the file or directory to be checked.

Return value:
If the file or directory exists, it returns true; if the file or directory does not exist, it returns false.

Example:
The following is a sample code to demonstrate how to use the file_exists() function to check whether a file or directory exists.

<?php
// 检查文件是否存在
$file = 'example.txt';
if (file_exists($file)) {
    echo "文件存在。";
} else {
    echo "文件不存在。";
}

// 检查目录是否存在
$dir = 'example_dir';
if (file_exists($dir) && is_dir($dir)) {
    echo "目录存在。";
} else {
    echo "目录不存在。";
}
?>

In the above example, a file path variable $file is first defined, and the file_exists() function is used to check whether the file exists. If it exists, output "The file exists.", otherwise output "The file does not exist.".

Next, a directory path variable $dir is defined, and the file_exists() function and is_dir() function are used to check whether the directory exists. If it exists and is a directory, output "The directory exists.", otherwise output "The directory does not exist.".

Note:

• The file_exists() function can be used to check files or directories in the local file system, or it can also be used to check the existence of remote files, just in the parameters Just specify the corresponding URL.
• The file_exists() function does not distinguish between files and directories. If the parameter specifies a directory, the function will also return true.
• The file_exists() function has no restrictions on the accessibility of files or directories, but only returns the status of whether the file or directory exists.
• Before using the file_exists() function, it is recommended to use the is_readable() function or is_writable() function to determine whether the file is readable or writable to avoid errors caused by permission issues.

Summary:
The file_exists() function is an important function in PHP used to check whether a file or directory exists. In daily PHP programming, it is often necessary to determine the existence of files or directories. This function can be easily achieved using the file_exists() function. Whether it is a local file or a remote file, you can use the file_exists() function to check the existence of a file or directory. The return value of this function is a Boolean value indicating whether the file or directory exists. Combined with other file processing functions, further operations on files or directories can be achieved. When using the file_exists() function, pay attention to the reasonable use of conditional judgments to ensure the correctness and safety of the program.

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