How to print name of variable in PHP?

Question

I'm writing a simple script for my webby that would send me an e-mail in case error 500 happens. I want to dump all possible variables, sessions, POSTs or whatever, present at time when error happened, so I can analyze the problem as precise as I can.

Here's the code I have for now:

function variable_name( &$var ) {
    $var_name = array_search( $var, $GLOBALS );
    return "{$var_name} = \"{$var}\"";
}

$bar = "whatever";

echo variable_name( $bar ); // bar = "whatever"

It's checking just $GLOBALS, but I need something that would check and print also $_POST, $_SESSION, class fields etc. I googled a bit and found just complicated functions that seem like an overkill for such easy task. Is there anything simple for this purpose or should I simply write a function for each of variable types?

Can't you just print_r everything you want dumped into the eMail message body, e.g. superglobals, debug_backtrace, etc? — Gordon
– Gordon, Commented Feb 10, 2010 at 12:53
What if there is more than one variable with the same value? Or if the variable is not in the global scope? — Gumbo
– Gumbo, Commented Feb 10, 2010 at 12:53
@Gordon: As far as I know print_r returns always 1, so I cannot. I could use var_dump tho. But it's not the point of question. I'm just wondering if it's possible to print name of variable. Sorry if I used misleading example. — Ondrej Slinták
– Ondrej Slinták, Commented Feb 10, 2010 at 12:55
@Ondrej: print_r($var, true) -- or for other functions which don't have an option to return instead of print, use Output Buffering. — nickf
– nickf, Commented Feb 10, 2010 at 12:59
Sorry, my fault, didn't realize it. However, it doesn't show me name of variable, and that's the whole point of question. get_defined_vars() seems to be a right answer. — Ondrej Slinták
– Ondrej Slinták, Commented Feb 10, 2010 at 13:04

ax. · Accepted Answer · 2010-02-10 13:02:49Z

5

use get_defined_vars():

This function returns a multidimensional array containing a list of all defined variables, be them environment, server or user-defined variables, within the scope that get_defined_vars() is called.

this includes $GLOBALS (since PHP 5.0.0), $_POST, $_SESSION, etc.

edited Feb 10, 2010 at 13:02

answered Feb 10, 2010 at 12:53

ax.

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1 Comment

Ondrej Slinták Over a year ago

Exactly what I needed. Appreciated :)

Community · Accepted Answer · 2023-11-17 19:42:58Z

1

Have you tried the get_defined_vars function ? https://www.php.net/manual/fr/function.get-defined-vars.php

edited Nov 17, 2023 at 19:42

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answered Feb 10, 2010 at 12:54

Zed-K

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Comments

Peter Perháč · Accepted Answer · 2010-02-10 12:54:58Z

1

Ondrej, try the print_r function. Look it up in the manual, it's really helpful at times. Notice it also takes an optional second parameter which is useful when you want to log the output to a file or db instead of just printing it to screen.

answered Feb 10, 2010 at 12:54

Peter Perháč

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ghostdog74 · Accepted Answer · 2010-02-10 12:56:44Z

1

how about get_defined_vars ? check out get_defined_functions and get_defined_constants as well

answered Feb 10, 2010 at 12:56

ghostdog74

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Sarfraz · Accepted Answer · 2010-02-10 12:58:55Z

0

but I need something that would check and print also $_POST, $_SESSION, class fields etc.

How about this:

function variable_name(&$var) {
    $var_name = array_search( $var, $_POST); // or you can put $_GET, $_SEESION,etc 
    return "{$var_name} = \"{$var}\"";
}

answered Feb 10, 2010 at 12:58

Sarfraz

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