What is the best way to perform a dependent addition/subtraction operation?

Question

It is common when one is at the beginning to come across this doubt.

I have to perform an operation that is dependent on a condition :

Example 1

$operacao = 'somar';

$valor1 = 5;
$valor2 = 10;
$saldo = null;

if($operacao == 'somar'){
    $saldo = $valor1 + $valor2;
}else{
    $saldo = $valor1 - $valor2;
}

if($saldo != null){
    echo $saldo;
}

Example 2

$operacao = 'somar';

$valor1 = 5;
$valor2 = 10;
$saldo = null;

$valor2 *= (($operacao == 'somar') ? 1 : -1);
$saldo = $valor1 + $valor2;

if($saldo != null){
    echo $saldo;
}

Question

What is the best way to accomplish this task, so that it does not occupy many lines, nor much memory?

Answer 1

It really tastes like.

Many people like the first because it seems clearer.

For me both are clear. Those who understand the programming can understand well any one of them.

Some people will say that the second example is a way clever (Clever) to do the same. And this can be good or bad depending on the context. Often the term is used pejoratively.

I would probably do so, after all the second example is not equivalent to the first:

$operacao = 'somar';
$valor1 = 5;
$valor2 = 10;
$saldo = null;
$saldo = $valor1 + $valor2 * ($operacao == 'somar' ? 1 : -1);
if ($saldo != null) echo $saldo;

Or you could use:

$saldo = $valor1 + ($operacao == 'somar' ? $valor2 : -$valor2);

Maybe I had a function for that, simply:

function InvertSignalConditional($value, $condition) {
    return $condition ? -$value, $value)
}

I put in the Github for future reference.

Note the inversion I did to be correct, after all you want the inversion if the condition is true.

In some cases one can opt more for one than the other for being more expressive of what the intention is. Some will say that the first example of the question is more expressive. This is an imperative way of seeing things, for those who know functional programming, which is much more expressive than the imperative, know that the second example is preferred.