echo variable's value in code

mikawhat

I have the following statement as a variable

$statement = '$cat_id > 5 && cat_id <= 20';

so i want to use the value ($cat_id > 5 && cat_id <= 20) inside an if statement... something like:

if ($cat_id > 5 && cat_id <= 20) {
echo "OK";
}

i've tried using eval or $$ but i'm not familiar with them and i'm probably doing something wrong....

dagon

since the latter is fine (and standard practice) why would you want to do the former (not standard practice)?

bradgrafelman

One solution would be to modify the $statement variable like so:

$statement = 'return $cat_id > 5 && $cat_id <= 20;';

That way you could then use [man]eval/man on the variable in an if() statement. Note that I also added a missing dollar sign on the second instance of 'cat_id' - remove this if you actually did have a constant defined called "cat_id".

As dagon asked, however, I would be interested to know why you're doing this? As the old saying goes, "If eval() is the answer, then you must be asking the wrong question."

mikawhat

Thanks for your help!
I'm doing this because i believe it's the easiest way to achive what i want to. I'm trying to create a hotel reservation system, with $date_in and $date_out. I get all entries for booking of a specific room, and with a while loop i'm creating the $statement to check if room is booked for the specific date
e.g.

$c_date = .....current date
while (...) {
$date_in = $row[0];
$date_out = $row[1];
$statement .= '('.$c_date.' >= '.$date_in.' && '.$c_date .'<= '.$date_out.')';
if (...) { // just to avoid ending with ||
echo " || ";
} 
}

bradgrafelman;10903478 wrote:
One solution would be to modify the $statement variable like so:
$statement = 'return $cat_id > 5 && $cat_id <= 20;'; 
That way you could then use [man]eval/man on the variable in an if() statement. Note that I also added a missing dollar sign on the second instance of 'cat_id' - remove this if you actually did have a constant defined called "cat_id".

As dagon asked, however, I would be interested to know why you're doing this? As the old saying goes, "If eval() is the answer, then you must be asking the wrong question."

cahva

I would do that in a sql query itself. Something like this:

SELECT date_in,date_out, IF(CURDATE() >= date_in AND CURDATE() <= date_out,true,false) AS booked FROM ...

mikawhat

cahva;10903639 wrote:
I would do that in a sql query itself. Something like this:
SELECT date_in,date_out, IF(CURDATE() >= date_in AND CURDATE() <= date_out,true,false) AS booked FROM ...

hmm.. interesting! so you just check if (mysql_num_rows() == 1), which means it's booked, right?

cahva

Well not exacty.. I thought that you want to list all bookings so previous query would give you a field "booked" which is either true or false.