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Posted by Bob Winter on 06/17/05 17:18
nntp.charter.net wrote:
> I want to write a trace procedure and call it with variable names, and I am
> having trouble with the syntax. My goal is to have a procedure that will
> echo lines such as:
>
> Trace: $myvar="the contents of $myvar
>
> My attempt that didn't work is to write a function:
>
> function my_trace($m){
> echo ("\n<br>TRACE: $m = ");
> eval("\$t=\"$m\";");
> echo($t."<br>\n");
> }
>
> and call it with statements like:
>
> my_trace("\$my_var");
> my_trace("\$_ENV[\"COMPUTERNAME\"]");
>
> What am I doing wrong, and how should this be done? Also, should I post to
> a different group?
>
> Thanks,
> Gil Grodsky
> ggrodsky@charter.net
Try this script, it works for me:
$my_var = 'Hello world!';
function my_trace($m){ // pay attention to the use of single vs double quotes throughout
$q = substr($m, 1); // chop off the leading '$' in the variable name
@eval("global \${$q};"); // need to use global to get value of local variables into this function
// also need @ to supress warning caused by brackets in superglobal variables
eval("\$t = \${$q};"); // assign value of orginal $m to $t
echo ("<br />TRACE: $m = $t<br />"); // output
my_trace('$my_var'); // note the use of single quotes here
my_trace('$_ENV["COMPUTERNAME"]'); // note where the single quotes are used here
Hope it helps,
Bob
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