Is there any difference between the is_file and file_exists function?

Yes there are some differences:

file_exists () checks whether the directory or file exists as an argument.

is_file () The manual definition is

  

Tell whether the given file is a regular file.

     

Informs if the / string passed as argument is a regular file

According to SOen's response , some examples of non-regular files are:

• devices
• pipes
• sockets

Basically what the function does is check if the specified string ( $filename ) is valid or does not contain strange characters positive case checks if $filename represents a file, otherwise returns false .

I made some tests comparing the two functions, the result is table below

Project Structure

Raiz
  foo
    3.txt - Atalho.lnk 
  txt
    1.txt
    abců.txt
    ů.txt
  ů

<?php
   var_dump(is_file('foo')); //pasta
   var_dump(is_file('txt/1.txt')); //arquivo
   var_dump(is_file('C:\')); //device
   var_dump(is_file('txt/abců.txt')); //arquivo com caracter estranho
   var_dump(is_file('txt/ů.txt')); //arquivo com caracter estranho
   var_dump(is_file('txt/ů')); // pasta com caracter estranho

   var_dump(file_exists('foo')); //pasta
   var_dump(file_exists('txt/1.txt')); //arquivo
   var_dump(file_exists('C:\')); // device
   var_dump(file_exists('txt/ů.txt')); //arquivo com caracter estranho
   var_dump(file_exists('txt/abců.txt')); //arquivo com caracter estranho
   var_dump(file_exists('ů'); //pasta com caracter estranho

Result:

     X      |Pasta |Arquivo|Device|Pasta ou arquivo com caracter estranho
is_file     |false |true   |false |false
file_exists |true  |true   |true  |false 

The is_file returns true only if the path is from a file (not directory / symlink). file_exists does not make this distinction and returns true if "something" exists in the path.

EDIT (only to supplement)

There are functions equivalent to is_file to check directories and symlinks, these are is_link 1 and is_dir 2 .

Method documentation:

file_exists() - Check if a file or directory exists
is_file() - Informs if the file is a common file (not a directory)

References:

link
link

is_file checks whether the file is a valid / existing file. But it does not work if you only check directories.

var_dump(is_file('a_file.txt')) . "\n";
var_dump(is_file('/usr/bin/')) . "\n";

Return:

bool(true)
bool(false)

In contrast, file_exists also works to check for directories.

One point to get up is:

What is expected of a function that does / verifies more than one thing? Let it be slower in comparison to others. It would be interesting to do tests about this and see which works best in context.

References:

Manual: is_file , file_exists