Question

Consider:

if (a = 10)
{
   /* do something */
}

I am interested if it is a good thing to do or not and why as I have to face it quite often. Thank you in advance.

Please consider a more complex example. What would you prefer and why?

function getSomeData()
{
    return rand(0, 5);
}

First:

if ($result = getSomeData())
{
    print($result)
}

or Second:

$result = getSomeData();
if ($result)
{
    print($result);
}

Answer 1

In this particular example, the if is unnecessary, the return of the affectation is always 10.

The following would be more interesting:

if (a = b) 
{ 
    // do stuff 
}

In this case, I prefer surrounding it with another pair of parentheses, in order to clarify your intention to other coders:

if ((a = b)) 
{
    // do something
}

A good rule to remember is that if you have to think more than 10 seconds to understand a condition, maybe there is another way to express it.