Dynamic IF statement

Echilon

I have a dtring which I want to generate dynamically from user input, but I need to test the contents of the string as an if statement, for example:

$ifst = '1 == 1';
echo if($ifst) { echo 'blah'; }

I want PHP to interpret this as if(1 == 1), but it's just testing for the existence of the $ifst variable.

herve

With the help of eval() function I think you can do that .

Cf http://fr2.php.net/manual/en/function.eval.php

Echilon

I looked et eval(), but I can't figure out how to make it work. It seems to just evaluate PHP code.

Megahertza

This method is not the best but i'm sure it will work, use fopen() to create or edit a file. Just fwrite() to the file the code you want. Then include the file into the page.

herve

Look at examples in the above link.
this one for instance :

jkuckartz1984 at hotmail dot com
29-Jan-2006 01:01

<?php

$total2=5;
$total3=0;
$i=2;

if (eval("\$total".$i.";")) 
   {
       echo "eval: total2 is full<br>";
   } 
   else 
   {
       echo "eval: total2 is empty<br>";
   }

?>

So for your case, something like :

$ifst = '1 == 1';

if ( eval($ifst) ) 
{ 
    echo 'blah'; 
}

Echilon

Parse error: parse error, unexpected $ in /home/thanatos/public_html/izeit/releases/2.0/includes/test.php(4) : eval()'d code on line 1

Doesn't really work...

herve

Well "1 == 1" is not really fully correct anyway 🙂

What do you want to do precisely ?
Can you give us a bit more detailed explanation ?

Echilon

I thought if I could get the basics workin, I could customise the IF statement. I'm creating a flat file database version of my calendar script, iZeit

In MySQL mode, the categories for events are filtered out by grabbing the input from checkboxes, creating an SQL statement using 'AND category = 'cat1' or category = 'cat2''. This is then attached to the end of an sql statement and sent to the server to return the correct results.

With a flat file it becomes more difficult. I need to have something like

if(($category == 'cat1') || ($category == 'cat2'))

But I don't know which categories will be selected, hence the need for a dynamic IF statement. Once I can get '1==1' evaluating, I should be able to adapt it to my needs. I could post the source for the MySQL version if it would help.

Thanks for the help 🙂

herve

I suppose you can put the choosen categories into an array
and then do something like this :

// $category_array contains 'cat1' ,'cat2', etc.
// coming from the HTML form

// $event_list come from the file (DB), $event_category is the category 
// of the current event examinated inside the first foreach loop.

foreach ($event_list as $event)
{
    $found = 0;

foreach ($category_array as $search_category)
{
    if ($event_category == $search_category)
    {
        $found = 1;
    }
}

if ($found == 1)
{
    $echo 'blah';
}
}