variable operator

Anon

Hi,

I've got the following if-statement:

if ($age >= $searchage && $height <= $searchheight && $weight == $searchweight)

This is a part of the code I use for a 'search-form'. One can search for age, height and weight. In this example the operators are fixed. I'd like to give the searcher the option to define the operators for each variable, so for example one can search for both younger, older, exactly or anything but a given age. The most simple solution to me would be to replace the '>=' with $ageoperator and the '<=' with heightoperator etc. (all defined in the search-form). Is this possible, or are there other/ better ways to do this?

Thanx in advance, Michiel

mp96brbj

You can create a string called $operator and give it the values '>=' or '<='. Then you could use eval() to create the if-statement. Keep in mind that using eval() is usually (much?) slower than using raw code, so use it conservatively.

An alternative version could be to create a function that decides which operator to use. Let the function decide which operators to compare the variables with, and then return true or false.

This:
if ($age >= $searchage && $height <= $searchheight && $weight == $searchweight)

...could become:
if (myFunction())

Anon

Hi Bjorn,

thanx for your reply. However I still have a question. How should I use the eval()-function? I read about the function on php.net, but I could not figure out in what way I could use it to solve my problem. Could you perhaps post a little example??

Thanx, Michiel

mp96brbj

Alright, I'll combine eval() with the separate-function approach here. For brevity I only use your $age variable in the example.

function foo($thing1, $operator, $thing2)
{
eval("\$r = ($thing1 $operator $thing2) ? true : false;");
return $r;
}

$operator = '<=';

if (foo($age, $operator, $searchage))
print 'Yes!';
else
print 'No!';

mp96brbj

Alright, I'll combine eval() with the separate-function approach here. For brevity I only use your $age variable in the example.

function foo($thing1, $operator, $thing2)
{
eval("\$r = ($thing1 $operator $thing2) ? true : false;");
return $r;
}

$operator = '<=';

if (foo($age, $operator, $searchage))
print 'Yes!';
else
print 'No!';

Anon

Thanx a lot Bjorn! This sure saves me a lot a coding when I want to perform searches with multiple variables! I do now understand what the eval()-function does, so I might use that approach more often.

Greetz, Michiel