Question

I would like to be able to output the name of a variable, along with that variable’s value. My use case is something close to a debug situation, but I’m actually building a proof of concept for other developers and managers so we can talk about things like input filtering. Anyway…

The output HTML is currently a table, but that shouldn’t matter. I can of course, just print out the name and then the contents in the HTML, but that gets tedious and is prone to typing errors. I’d like a function that I could call with the variable name, or a string with the variable name as the argument, and have that function generate the appropriate HTML for display. This doesn’t appear to work.

This works:

<tr><td>$variable</td><td><?php print $variable?></td></tr>

This doesn’t:

function rowFromVar($varname) {
    $result  = "<tr>";
    $result .= "<td>\$$varname</td>";
    $result .= "<td>" . $$varname . "</td>";
    $result .= "</tr>";
    return $result;
}
// now in the HTML...
<table><?php print rowFromVar("variable");?></table>

The variable variable $$varname is always empty. Notice that I’m passing in the name of the variable as a string, rather than trying to pass in the variable itself and work with it. I know that there be dragons that way. Instead, I’m trying to pass in the name of the variable as a string, and then use a variable variable (yeah, I know) to return the value of the original variable. That appears not to work either, and I’m betting it’s a scope issue.

Is there any good way to accomplish what I’m looking for?

Answer 1

You need declare your variable global within the function so that it references the global version. Adding this line at the start of your function should fix the problem:

function rowFromVar($varname) {
    global $$varname;
    $result  = "<tr>";
    $result .= "<td>\$$varname</td>";
    $result .= "<td>" . $$varname . "</td>";
    $result .= "</tr>";
    return $result;
}