CODEWITHSUNDEEP
phpperformance
AgelessEssence
AgelessEssence

Reputation: 6731

php, realpath versus realpath + file_exists usage

by performance reasons we should use only realpath() instead of realpath() + file_exists() when checking existence of a file or directory ??

CASE A ::

if(realpath(__DIR__."/../file.php")===false)

CASE B ::

if(file_exists(realpath(__DIR__."/../file.php"))===false)

i think CASE A do the job, and CASE B do the job two times.

Upvotes: 5

Views: 3760

Answers (3)

cwallenpoole
cwallenpoole

Reputation: 82028

Not only is case B redundant (as realpath returns false if the path cannot be resolved or the file does not exist as per the docs), if the file does not exist, that is a bit silly.

Since this statement will return FALSE:

realpath(__DIR__."/../file.php");

This:

file_exists(realpath(__DIR__."/../file.php"));

Is really this:

file_exists(FALSE); //!
As a side note: `realpath` will never return a "FALSY" value. By this I mean that it will never return something which `== FALSE` but does not `=== FALSE` (eg. `NULL`, `''`, 0, array()). Why? Well, the real path will always include a reference to the root — `/` in *nix systems (Mac, Unix, Linux) and `C:\` in Windows, and those two strings will evaluate to true when used as a boolean (say in an if, while, or for loop). This means you can just do: 
if(!realpath(__DIR__."/../file.php")) // do something

Or, if you need to actually have the realpath, you can:

if(!($path = realpath(__DIR__."/../file.php")))
   // file does not exist
else
   // $path is now the full path to the file

Upvotes: 9

Mac_Cain13
Mac_Cain13

Reputation: 3633

They are nearly the same, but not exactly!

Case A will check if the path exists, realpath will return non-false values if the path after expanding it will point to a file or folder. Also if you pass realpath a null-value or an empty string it will return the current folder.

Case B can also check if the returned path is a regular file (as opposed to a directory!). If realpath resolves the path to an folder, an is_file call will return false and you can handle it from there.

So realpath will check if there is a file or folder (or symlink link thereto) at the given path and will expand empty values to the current directory. The extra is_file check can ensure you're working with a file not a folder.

Use case B (with is_file instead of file_exists) if you want to be sure you're working with a file, use case A if folders are also okay. :)

file_exists (in contrast with is_file) returns true for directories as well.

Upvotes: 1

landons
landons

Reputation: 9547

That is correct. realpath() will return false if the file does not exist. Case B is redundant.

https://www.php.net/realpath#refsect1-function.realpath-returnvalues

Upvotes: 2

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