Where to put arrays with constant value that will be accessed many times?

Question

I have some arrays storing the possible parameters for some 3D printer commands. I use this to check if the command is legal. I am confused about where I should put these ar

Answer 1

I think that the defining array a property is making more sense, as arrays defined inside the methods are created on every call.

But I want to make another point. If you have rather large arrays to look up value in, it is more important how you structure them. I would suggest this:

array(
    82 => true,
    83 => true,
    84 => true,
    104 => true,
    106 => true,
    107 => true,
    109 => true,
    140 => true,
    190 => true
);

array(
    0 => true,
    1 => true,
    20 => true,
    21 => true,
    28 => true,
    90 => true,
    91 => true,
    92 => true
);

array(
    0 => true,
    1 => true
);

Having this structure you can use isset (O(1)) instead of in_array (O(n)).

Here are some other questions regarding isset vs. in_array:

• what is faster: in_array or isset? [closed]

• in_array vs isset - perfomance

And here are some posts with benchmarks:

• http://maettig.com/1397246220
• Tip Of The Day: isset() vs. in_array()

The last one is rather old, but I think the ratio holds.

So to sum up. When you use isset the searching time is constant (it actually might vary, but this can be ignored). When you use in_array the searching time depends on element position (and so on array size). Even on small arrays isset works faster.