Summary of how to get file extension in PHP

This time I will bring you a summary of how PHP obtains file extensions. What are the precautions for PHP to obtain file extensions? The following is a practical case, let's take a look.

This is a written test question I encountered when applying for an internship:

Use more than five methods to obtain the extension of a file.

Requirements: dir/upload.image.jpg, find .jpg or jpg,

Must use PHP's own processing function for processing, the method cannot be obviously repeated, and can be encapsulated into a function, For example, get_ext1($file_name), get_ext2($file_name)

The following are five methods I summarized by referring to online information. They are all relatively simple and do not say much. Say, go directly to the code:

Method 1:

function getExt1($filename)
{
   $arr = explode('.',$filename);
   return array_pop($arr);;
}

Method 2:

function getExt2($filename)
{
   $ext = strrchr($filename,'.');
   return $ext;
}

Method 3:

function getExt3($filename)
{
   $pos = strrpos($filename, '.');
   $ext = substr($filename, $pos);
   return $ext;
}

Method 4:

function getExt4($filename)
{
   $arr = pathinfo($filename);
   $ext = $arr['extension'];
   return $ext;
}

Method 5:

function getExt5($filename)
{
   $str = strrev($filename);
   return strrev(strchr($str,'.',true));
}

I believe you have mastered it after reading the case in this article For more exciting methods, please pay attention to other related articles on the php Chinese website!

Recommended reading:

Detailed explanation of the steps for PHP to use file_get_contents to send http requests

PHP implements random elimination algorithm

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