获取 PHP 文件/图像扩展名

Question

I'm trying to get a images file extension and add some random number. Like 348678423.jpeg, 343344343.jpg, 32434343.gif, 3434343.png etc..

So following is my php code:

function getExtension($str)
{
     $i = strrpos($str,".");
 if (!$i) { return ""; }
 $l = strlen($str) - $i;
 $ext = substr($str,$i+1,$l);
 return $ext;
}
  @$extension = getExtension($file);
   $extension = strtolower($extension);
  $image_named_uniq = uniqid().'.'.$extension;  

But when i echo this variable $image_named_uniq it's just show the random number, Like: 50aa5a2e0f425. It's should be show 50aa5a2e0f425.jpg etc..

What is wrong in my code?

Answer 1

如果您只需要扩展名：

echo end(explode('.', $str));

Answer 2

You can use pathinfo() to get the extension

$path_parts = pathinfo($filename);
echo $path_parts['extension'];

Answer 3

The answer posted by @jereon is correct, and the easiest way to do this.

However, if you would like to extract more information about the file without using explode and end, you can simply use the PHP built in pathinfo() function.

Reference: pathinfo()

<?php
    $path_parts = pathinfo('/www/htdocs/inc/lib.inc.php');

    echo $path_parts['dirname'], "\n";
    echo $path_parts['basename'], "\n";
    echo $path_parts['extension'], "\n";
    echo $path_parts['filename'], "\n"; // since PHP 5.2.0
?>

This will return

/www/htdocs/inc
lib.inc.php
php
lib.inc

As $filename is an array, you need to loop through it in order to read it into pathinfo() . This can be done very easily using a foreach loop like so:

// Loop through the filenames array
foreach($filename as $value){
    // Retrieve the path parts of each individual file
    $path_parts[] = pathinfo($value);
}

// Write out the path parts array
print_r($path_parts);

Answer 4

The easiest way would be to use pathinfo() . Note that the result is based on the filename and no introspection on the file is performed (eg. the image logo.jpg renamed to logo.php will result in a .php file extension. Use the fileinfo extension if you want to get the filetype by it's contents)