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.

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