PHP Microbenchmarking（变量与条件语句）

Question

This question might be "a bit out there". But more or less it's microbenching code, but it's to improve my standards and general knowledge of PHP's backend.

SO! Here I go, my question! Would calling a variable twice require less memory (and load on CPU) than calling an additional else condition in PHP? Which requires more resources? And why?

The Below examples:
A, shows calling a variable twice and B, shows calling an additional else condition. Both have the same end result, of course.

Any additional references to any answers (responds) would be highly appropriated too! If possible.

Example A:

$a = 1;
if (isset($array['a']))
{
    $a = $array['a'];
}

$b = NULL;
if (isset($array['b']))
{
    $b = $array['b'];
}

Example B:

if (isset($array['a']))
{
    $a = $array['a'];
}
else
{
    $a = 1;
}

if (isset($array['b']))
{
    $b = $array['b'];
}
else
{
    $b = NULL;
}

Answer 1

I created a mini benchmark, to see which is faster. The following evaluates both functions exactly 100 times. Inside of the two functions, they evaluate your examples exactly 100,000 times. On my home Ubuntu web server, the output is similar to this.

6.0754749774933 = Giving the variable a default value.

4.8433840274811 = Using an else statement instead.

The second example (else statements) is two seconds faster, however the example is being executed 10,000,000 (10 million) times. In a real-life example, the readability of the code and what your team prefers is more important than saving a few milliseconds.

To answer your question, there is almost 0 difference when using either method.

If you want my opinion, I prefer the second example.

Here is the benchmarking code I used. http://phpfiddle.org/api/raw/8nm-d72