PHP function introduction: file_exists() function

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Release: 2023-11-03 18:28:01
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PHP function introduction: file_exists() function

Introduction to PHP functions: file_exists() function, specific code examples are required

In PHP programming, we often need to determine whether a file exists. At this time, we can use PHP The built-in file_exists() function. This article will introduce how to use the file_exists() function and some precautions.

1. Introduction to file_exists() function

The file_exists() function is used to check whether a file or directory exists. If it exists, it returns true, otherwise it returns false. This function can accept a parameter, which can be a file name or directory name, and supports the inspection of local files and remote files.

2. Function syntax

file_exists(file)

Parameter description: file - file name or directory name, if it is a remote file, it needs to be http:// or ftp:// starts.

Return value: Returns true if the file or directory exists, otherwise returns false.

3. Sample code

The following code demonstrates how to use the file_exists() function.

//Check whether the local file exists
$file='./test.txt';
if(file_exists($file)){
echo 'File exists';
}else{
echo 'File does not exist';
}

//Check whether the remote file exists
$file='http://www.example.com/test. txt';
if(file_exists($file)){
echo 'The file exists';
}else{
echo 'The file does not exist';
}

//Check whether the directory exists
$dir='./example';
if(file_exists($dir)){
echo 'The directory exists';
}else{
echo ' The directory does not exist';
}

4. Notes

  1. The file_exists() function can only check whether the file or directory exists, and cannot determine whether it is a file or a directory.
  2. The file_exists() function is only suitable for checking whether local files and remote files exist. It cannot determine whether local files are readable or writable.
  3. When using the file_exists() function and other functions to operate the same file, you need to pay attention to the issue of file locking.

In short, the file_exists() function is used very frequently in PHP programming. It can easily determine whether files and directories exist, thereby reducing code complexity and improving coding efficiency.

The above is the detailed content of PHP function introduction: file_exists() function. For more information, please follow other related articles on the PHP Chinese website!

source:php.cn
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