[RESOLVED] Variables within Variables in Functions

[h_a_l_]

Hello,
I have created the following function.

function matrix($r)
{
	$m1 = file("m1.txt");
	$m1r{$r} = explode(" ",$m1[$r]);
	print_r($m1r[$r]);
}

You give it a line number ($r) and it returns that line from m1.txt as an array.
Each line in m1.txt is a series of numbers separated by spaces. This all works fine.

However lets say I have several text files and do not want to create a separate function for each array. How do I replace 1 with a variable?

I have tried $n and {$n} but receive errors.

This is part of a larger script and I am stuck on something so simple. 🙁
Any tips much appreciated,

Thanks,

Hal

[HalfaBee]

Maybe something like this.

function matrix($r,$file) 
{ 
    $m1 = file($file); 
    $m1r{$r} = explode(" ",$m1[$r]); 
    print_r($m1r[$r]); 
}
matrix( 1,'xyz.txt');
matrix( 4,'abc.txt');

Is my homework done?

[h_a_l_]

Thanks for the reply, and heaps of shame on me...

However still curious to know if the 1 in $m1 and in the file name can be provided to the function via another parameter ($n)?

Apart from that, I need to think a little more about the rest of the script.

[etully]

You can make variable variable names... but I don't think you need to do that for this project.

First, consider this:

function matrix($r,$n)
{
    $m1 = file("m".$n.".txt"); 

That will open the filename that starts with the letter "m" followed by the number you passed in. In your sample function, the variable can ALWAYS be $m1 even if it's reading from a text file called m23.txt.

Of course, if you are going to be reading mutliple files, you can easily use an array like this:

function matrix($r,$n)
{
    $m = array();
    $m[$n] = file("m".$n.".txt"); 

That way, $m[4] will have the contents of m4.txt and $m[23] will have the contents of m23.txt.

But if you really must have variable variable names, you can do something like this:

$x = 1;
$v = "m" . $x;
$$v = "this is a string";

echo $m1 . "\n\n";

[h_a_l_]

Thank you for the detailed reply Etully.

I never even considered putting the different files in separate arrays. Will see what works best here and will bear your suggestion in mind in the future.

Furthermore, my problem with variables in variables (or even multiple variables in variables) was a syntax one. It appears you cannot have any other characters inbetween variables in variable names.

Thats alot of of variables. 🙂

Thanks for the help guys. Resolved!