Merge PHP const arrays to new const array without nesting

Question

Let's say I have 3 const arrays:

const A = ["a", "aa", "aaa"];
const B = ["b", "bb"];
const C = ["c"];

I now want to merge / combine those into another const D array without nesting them. How can I do this?

Basically I'm looking for something like array_merge(), but for constants, because as we all know, expressions can't be assigned to constants.

The result I'm looking for is

const D = ["a", "aa", "aaa", "b", "bb", "c"];

which is what

const D = array_merge(A, B, C);

would provide me with, if expressions were allowed for constants.

I've tried

const D = A + B + C;

but that leaves me with just the contents of A in D.

I've also tried

const D = [A, B, C];

but, as expected, this results in an array of arrays [["a", "aa", "aaa"], ["b", "bb"], ["c"]] which isn't what I'm looking for.

Martin Prikryl · Accepted Answer · 2024-11-22 09:26:45Z

28

You can use the spread operator for arrays (also known as unpacking) since PHP 7.4 (initial RFC):

const D = [...A, ...B, ...C];

I don't think there is any (other) way to do this with previous versions.

Martin Prikryl

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answered Jan 5, 2020 at 19:08

Jeto

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1 Comment

Doesn't work with string keys before 8.1

jpkrc · Accepted Answer · 2025-01-08 11:13:45Z

1

Bit late to this question but for those with PHP < 7.4:

If you provide unique keys for each of the initial separate array elements, then array addition works.

Example:

const A = ["a", "aa", "aaa"];
const B = [10 => "b", 11 => "bb"];
const C = [20 => "c"];
const D = A + B + C;

answered Jan 8 at 11:13

jpkrc

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