variable variables

combining variables

[WhosAWhata]

this is a simplified version of the code that is running through many pieces of my site

$c1 = "hello";
$a = 1;
$b = c$a;
echo "$$b";

the only way i can get this to work is if i first compile $$b with another function

$c1 = "hello";
$a = 1;
$b = c$a;
// $b = functionOfSomeSort($$b);
echo "$b";

what would be the best "functionOfSomeSort()" to use?

[jamesa]

Not sure what your asking, but I know that this will work:

$c1 = "hello";
$a = 1;
$b = "c" . $a;
echo $$b;

Does that help at all? :)

[ergophobe]

Or in some situations

eval("\$b = c$a1;");

depending on what your "unsimplified" version is. Clearly, in your simplified example, the previous post offers a better solution.

Tom

[WhosAWhata]

works perfect thanks
if you don't mind, how exactly does it work? i don't seem to understand this line

$b = "c" . $a;

it works but i don't know how it works
thank you

[coopster]

1. The letter "c" is being concatenated to the value of the variable $a (which is "1") and that value is being assigned to the variable $b. Therefore, $b becomes "c1".
   
2. Then, by taking the variable variable [php.net] of $b ($$b is a variable variable), you get the value of $c1.

I once tried to explain variable variables a bit more clearly, this read may help:
[webmasterworld.com...]

[jamesa]

Yea, by putting "c" in quotes it makes the "c" a string. Otherwise PHP expects another variable or a function (or perhaps an integer). Actually come to think of it,

$b = "c$a";

would probably work too. As long as the quotes are there it treats it as a string.

[WhosAWhata]

thanks that makes sense

[dcrombie]

$c1 = "hello";
$a = 1;
echo ${"c$a"};

;)

[ergophobe]

echo ${"c$a"};

I would not have thought of that one!

[jatar_k]

the same applies inside the braces

$c1 = "hello";
$a = 1;
echo ${"c" . $a};

[ergophobe]

the same applies inside the braces

But as the previous poster pointed out, substitution within double quotes works.

$c1= "hello jatar_k";
$a = "1";
echo ${"c$a"};

This outputs "hello jatar_k" just as promised.

Tom

[jatar_k]

true but sometimes one style is easier to read than others for any particular person.

both work exactly the same

echo ${"c$a"};
echo ${"c" . $a};

I always use the second because I find it much easier to read. I just mentioned it to add to the many forms for the same function. ;)

[g1smd]

Ah, this simplifies some code that I was working on too.

I had used a two dimensional array.

This variable variable stuff will actually be better in many ways, I think.

[WhosAWhata]

thanks guys,
code works great
before this i was using
$a1 = "hi";
$b = 1;
$c = a$b;
$c = stripslashes(htmlspecialchars($$c));
echo $c;

as you can see,
echo ${"a$b"};
works ALOT better