Array range with exceptions

Question

In the PHP function range there are a start point, a end point and a step point.

is it possible to create an array with numbers, in which some values should not exist?

$hundred_tens = range(120, 190, 10);

I need the numbers 220,230,...290 ... 920,930..990, but not 200,210 ...900,910.

My solution:

$hundreds = range(100, 800, 100); 
foreach ($hundred_tens as $value) {
    $add_numbers[] = $value + $hundreds[0];
    $add_numbers[] = $value + $hundreds[1];
    $add_numbers[] = $value + $hundreds[2];
    $add_numbers[] = $value + $hundreds[3];
    $add_numbers[] = $value + $hundreds[4];
    $add_numbers[] = $value + $hundreds[5];     
    $add_numbers[] = $value + $hundreds[6];
    $add_numbers[] = $value + $hundreds[7];
}
$all_hundred_tens = array_merge($hundred_tens, $add_numbers);

I have add in a foreach every array value $hundreds to in a new array and merge this array with $hundred_tens.

rjdown · Accepted Answer · 2015-08-18 00:11:52Z

1

You can either loop through your entire range and exclude the unnecessary numbers

$hundred_tens = array();
foreach (range(100, 800, 10) as $number) {
    if ($number % 100 !== 0 && $number % 100 !== 10) {
        $hundred_tens[] = $number;
    }
}

or you can merge smaller ranges:

$hundred_tens = array_merge(range(120, 190, 10), range(220, 890, 10), range(920, 990, 10));

Which one is better depends on how many exclusions you have, and if they are together in the list.

Ref my comment below about for ( being faster, here's an example (only one line is different)

$hundred_tens = array();
for ($number = 100; $number <= 1000; $number += 10) { 
    if ($number % 100 !== 0 && $number % 100 !== 10) {
        $hundred_tens[] = $number;
    }
}

edited Aug 18, 2015 at 0:11

answered Aug 17, 2015 at 23:46

rjdown

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4 Comments

Grischa Over a year ago

Thank you, so I have to merge it to 7 ranges like that? I don't want to have 300,310,400,410,500,510,600,610,700,710,800,810,too.

rjdown Over a year ago

Then it will be better to just do one range and check the numbers. I'll update the answer

rjdown Over a year ago

Note that for ($number = 100; $number <= 800; $number += 10) { will run a lot faster while doing exactly the same thing, but for this small range you won't see a difference.

Grischa Over a year ago

Ok, but I need later a bigger amount of numbers in an array like this with more exceptions. It would be great, if you could show me an example with a for loop with also fill all needed numbers in an array. (end of the array should be 990 or 1000 in the first code)

Tomasz Nguyen · Accepted Answer · 2015-08-17 23:38:26Z

1

Basically, you create a for-loop starting from 220 till 910 in steps of 10. In the loop you check whether the number is a hundred or a hundred plus ten. If it is not, then add the number to the array.

To check whether a number is divisable by 100, you could use the module operator %.

So, a % 100 == 0 will result in true, if a is divisable by 100 and false otherwise. For hundreds plus ten, you could do: (a - 10) % 100 == 0.

answered Aug 17, 2015 at 23:38

Tomasz Nguyen

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