PHP Programming - newbie question: using $_POST inside of array parameters?

Author

newbie question: using $_POST inside of array parameters?

kurrent@gmail.com

2006-08-29, 6:58 pm

I am relatively new to PHP and just have a question regarding $_POST to
get a value passed via a form to be included of the parameter of an
array I am using:

eg.

<?

$a array = ("1", "2", "3");

echo "<form method=POST>

<select name=b size=1>
<option value=1>number1</option>
<option value=2>number2</option>
<option value=0>number3</option>
</select>

<input type=submit name=Submit>

</form>";

echo "$a[$b]";

Since I have a global variables turned off, and would like to keep
learning with them off, I am stumped on to get that value passed

>From my understanding, I see that $_POST[b] would successfully retrive
the value of the $b variable. So i've tried many variants on the syntax
but no luck (e.g. "$a[$_POST[b]]) etc...

any help is much appreciated :) thanks!

Alvaro G. Vicario

2006-08-29, 6:58 pm

*** kurrent@gmail.com escribió/wrote (29 Aug 2006 14:24:02 -0700):
> <select name=b size=1>
> <option value=1>number1</option>
> <option value=2>number2</option>
> <option value=0>number3</option>
> </select>

> the value of the $b variable. So i've tried many variants on the syntax
> but no luck (e.g. "$a[$_POST[b]]) etc...

I'm unsure of what you're trying to accomplish, but you must learn the
syntax of the different types of identifiers:

$foo -> variable
foo() -> function or class
'foo' -> string
"foo" -> string with variables
foo -> constant

So $_POST[b] won't make any sense unless you previously define a constant
called b:

define('b', 'whatever');

I suppose you just forgot the quotes.

Your sample form creates the following array:

$_POST['b']='1';
$_POST['Submit']='Enviar consulta';

You can see it yourself with var_dump($_POST).

--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
+- Mi web de humor con rayos UVA: http://www.demogracia.com
--

onembk

2006-08-29, 6:58 pm

On 2006-08-29 15:24:02 -0600, kurrent@gmail.com said:

> I am relatively new to PHP and just have a question regarding $_POST to
> get a value passed via a form to be included of the parameter of an
> array I am using:
>
> eg.
>
> <?
>
> $a array = ("1", "2", "3");
>
> echo "<form method=POST>
>
> <select name=b size=1>
> <option value=1>number1</option>
> <option value=2>number2</option>
> <option value=0>number3</option>
> </select>
>
> <input type=submit name=Submit>
>
>
> </form>";
>
> echo "$a[$b]";
>
>
> Since I have a global variables turned off, and would like to keep
> learning with them off, I am stumped on to get that value passed
>
>
> the value of the $b variable. So i've tried many variants on the syntax
> but no luck (e.g. "$a[$_POST[b]]) etc...
>
> any help is much appreciated :) thanks!

You need to either

echo $a[$_POST['b']];

or

$b = $_POST['b'];
echo $a[$b];

(the b is in quotes).

Norman Peelman

2006-08-29, 9:57 pm

<kurrent@gmail.com> wrote in message
news:1156886642.624061.318070@m73g2000cwd.googlegroups.com...
> I am relatively new to PHP and just have a question regarding $_POST to
> get a value passed via a form to be included of the parameter of an
> array I am using:
>
> eg.
>
> <?
>
> $a array = ("1", "2", "3");
>
> echo "<form method=POST>
>
> <select name=b size=1>
> <option value=1>number1</option>
> <option value=2>number2</option>
> <option value=0>number3</option>
> </select>
>
> <input type=submit name=Submit>
>
>
> </form>";
>
> echo "$a[$b]";
>
>
> Since I have a global variables turned off, and would like to keep
> learning with them off, I am stumped on to get that value passed
>
>
> the value of the $b variable. So i've tried many variants on the syntax
> but no luck (e.g. "$a[$_POST[b]]) etc...
>
> any help is much appreciated :) thanks!
>

How about : echo "{$a[$_POST['b']]}";

Norm

Kimmo Laine

2006-08-30, 7:57 am

"Alvaro G. Vicario" <webmaster@NOSPAMdemogracia.com> wrote in message
news:rj72wmibg02j.622tzkodwvj7.dlg@40tude.net...
> *** kurrent@gmail.com escribió/wrote (29 Aug 2006 14:24:02 -0700):
>
>
>
> I'm unsure of what you're trying to accomplish, but you must learn the
> syntax of the different types of identifiers:
>
> $foo -> variable
> foo() -> function or class
> 'foo' -> string
> "foo" -> string with variables
> foo -> constant
>
> So $_POST[b] won't make any sense unless you previously define a constant
> called b:
>
> define('b', 'whatever');

That's not entirely true. if there is no constant named foo, it is
interpreted as "bare string", an unquoted string. Ie. it is treated just
like a string, but a warnign message is generated. So basicly $a[$_POST[b]]
would work. This is a bad practise and should be avoided always to
distinguish the difference between a constant and a string. Bare strings is
a terrible terrible feature implemented only for backwards compatibility, I
can't imagine anyone seriously using it. But it's there, and it works. A
programmer should be aware of the peculiar features of the language even
thou they aren't used.

--
"Ohjelmoija on organismi joka muuttaa kofeiinia koodiksi" - lpk
http://outolempi.net/ahdistus/ - Satunnaisesti päivittyvä nettisarjis
spam@outolempi.net || Gedoon-S @ IRCnet || rot13(xvzzb@bhgbyrzcv.arg)

mootmail-googlegroups@yahoo.com

2006-08-30, 7:57 am

Norman Peelman wrote:
> <kurrent@gmail.com> wrote in message
> news:1156886642.624061.318070@m73g2000cwd.googlegroups.com...
>
> How about : echo "{$a[$_POST['b']]}";
>
> Norm

Building upon that advice, there is a limitation when using
double-quoted strings in PHP which you should be aware of.

Double-quoted strings will be parsed for variables, however only of the
simplest types. Anything more complex needs to be encased in curly
braces { } in order to be evaluated.

So while you can do:
echo "$foo"; \\evaluates variable $foo
You cannot do:
echo "$foo['a']";
echo "$foo[$x]";
echo "$foo->x";

Instead, you must do:
echo "{$foo['a']}";
echo "{$foo[$x]}";
echo "{$foo->x}";

kurrent@gmail.com

2006-08-31, 6:57 pm

It worked, thanks alot for the feedback guys :)

much appreciated

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