Echo the actual Variable name

[Dawsons]

So i sit here thinking, and wondering...

say for example i have a variable called $definition_lon don

Say for exaple that has not set value...

Is it possible to echoe thew ACTUAL variable name into a document, rather
than the variables information?

Thanks for yout time, look forward to all replies :)

[Kimmo Laine]

Re: Echo the actual Variable name

"Dawsons" <stuart@3branch .co.uk> wrote in message
news:AahKf.3246 2$Fy4.29398@new sfe4-win.ntli.net...[color=blue]
> So i sit here thinking, and wondering...
>
> say for example i have a variable called $definition_lon don
>
> Say for exaple that has not set value...
>
> Is it possible to echoe thew ACTUAL variable name into a document, rather
> than the variables information?
>
> Thanks for yout time, look forward to all replies :)
>[/color]


I'm no sure what you are exactly looking for, but you could do something
like this:

echo 'Here is a list of all variables and their values defined in this
script:<br />';
print_r(get_def ined_vars());

--
"En ole paha ihminen, mutta omenat ovat elinkeinoni." -Perttu Sirviö
spam@outolempi. net | Gedoon-S @ IRCnet | rot13(xvzzb@bhg byrzcv.arg)

[samudasu]

Re: Echo the actual Variable name

echo '$definition_lo ndon is in a string';

[Ewoud Dronkert]

Re: Echo the actual Variable name

Dawsons wrote:[color=blue]
> Is it possible to echoe thew ACTUAL variable name into a document[/color]

function getvarname(&$va r)
{
$ret = '';
$tmp = $var;
$var = md5(uniqid(rand (), TRUE));

$key = array_keys($GLO BALS);
foreach ( $key as $k )
if ( $GLOBALS[$k] === $var )
{
$ret = $k;
break;
}

$var = $tmp;
return $ret;
}

$another = 'test';
$testvar = 'test';
echo getvarname($tes tvar); //echoes 'testvar'

--
E. Dronkert

[Dawsons]

Re: Echo the actual Variable name

Thank you very much, this is excellent!

"Ewoud Dronkert" <firstname@last name.net.invali d> wrote in message
news:dd6kv19jkb etderhetu39ioqk vq6nuta4n@4ax.c om...[color=blue]
> Dawsons wrote:[color=green]
>> Is it possible to echoe thew ACTUAL variable name into a document[/color]
>
> function getvarname(&$va r)
> {
> $ret = '';
> $tmp = $var;
> $var = md5(uniqid(rand (), TRUE));
>
> $key = array_keys($GLO BALS);
> foreach ( $key as $k )
> if ( $GLOBALS[$k] === $var )
> {
> $ret = $k;
> break;
> }
>
> $var = $tmp;
> return $ret;
> }
>
> $another = 'test';
> $testvar = 'test';
> echo getvarname($tes tvar); //echoes 'testvar'
>
> --
> E. Dronkert[/color]

[Oli Filth]

Re: Echo the actual Variable name

Dawsons said the following on 20/02/2006 10:51:[color=blue]
> So i sit here thinking, and wondering...
>
> say for example i have a variable called $definition_lon don
>
> Say for exaple that has not set value...
>
> Is it possible to echoe thew ACTUAL variable name into a document, rather
> than the variables information?
>[/color]

Maybe I'm missing something, but why can't you just do echo
'$definition_lo ndon'; ??

--
Oli

[Ewoud Dronkert]

Re: Echo the actual Variable name

Dawsons wrote:[color=blue]
> Thank you very much, this is excellent![/color]

Only works for globals though.

--
E. Dronkert

[Iván Sánchez Ortega]

Re: Echo the actual Variable name

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Hash: SHA1

Dawsons wrote:
[color=blue]
> say for example i have a variable called $definition_lon don
>
> Say for exaple that has not set value...[/color]

If it has no value, that varable name does not exist. Bye-bye.
[color=blue]
> Is it possible to echoe thew ACTUAL variable name into a document, rather
> than the variables information?[/color]

No, because a variable can have more than one, due to the way PHP handles
references. Suppose the following code:

<?php

$a = 42;

$b =& $a;
$c =& $a;
unset ($a);

?>

At this point, what is the name of the variable that holds "42"?? $b, $c,
both, or nobody??

For this issue, do not think that a variable is a variable. Think that a
variable is an entry in an ordered map (with internal pointers),
implemented as a hash table that can map two (or more) keys to the same
value.

Let me (try to) explain this concept in pseudo-C:

function foo()
{
int* a;
int* b;
inc* c;
a = b = c = malloc(sizeof(i nt));
*a = 42;
a = NULL;
}

This would have a similar behaviour than the PHP code I posted up there. In
PHP, variable names "point" to the value. A reference is a pointer to that
value. Storing a reference is making two entries on the variable hash
tables point to the same value. When no references to a value are found,
that memory is freed.

Variable management in PHP is quite complicated internally, with all that
duplicate-on-write stuff when making copies of complex variables. The kind
of stuff that operating systems do when you fork() a process.



I agree with Ewoud: you can transverse the $GLOBALS superglobal array to
search for your value, but if you have any references over there, you may
find lots of problems. Lots.

- --
- ----------------------------------
Iván Sánchez Ortega -i-punto-sanchez--arroba-mirame-punto-net

http://acm.asoc.fi.upm.es/~mr/

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