Array.concat

Concatenate with other arrays, and return the result as a new array.

Signature

fun concat[T](
    self,
    Array[T]... arrays,
) -> Array[T]thp
    

Parameters

• self: The callee.
• Array[T]... arrays: Multiple arrays to concatenate the current one to.

Return value

Array[T]: A new array that contains the elements from all arrays.

Description

Concatenates the elements of the callee and the elements of each array in the variable array. These values are returned in a new array.

If called without any aditional array it returns a new array with the elements of self.

The returned array is a new one. However, if the elements of the callee and the parameters are references, the returned array will contain references that point to the same memory. This is important if, for example, the arrays contain other arrays or objects.

Examples

Example concatenating 2 arrays:

val first  = [1, 2, 3]
val second = [4, 5, 6]

val result = first.concat(second)
assert_eq(result, [1, 2, 3, 4, 5, 6])thp
    

Example concatenating 3 arrays:

val first  = ["a", "b"]
val second = ["c", "d"]
val third  = ["e", "f"]

val result = first.concat(second, third)
assert_eq(result, ["a", "b", "c", "d", "e", "f"])thp
    

Example concatenating without any other array. In this case first and result are different arrays:

val first  = [1, 2, 3]

val result = first.concat()
assert_eq(result, [1, 2, 3])thp
    

Example concatenating an empty array with a filled array:

val first  = []
val second = [10, 20, 30]

val result = first.concat(second)
assert_eq(result, [10, 20, 30])thp
    

PHP interop

This method is directly compiled to array_merge. Since THP guarantees that arrays only have numbers as keys, this will never produce invalid values due to merging with an array with string keys.

If the arrays contain invalid keys (negative values, out of bounds) the merge is performed based on the insertion order, not the keys order, and the resulting array will have correct keys.

$array_1 = [2 => "a", 0 => "b"];
$array_2 = [1 => "c"];

var_dump(array_merge($array_1, $array_2));

array(3) {
  [0]=> string(1) "a"
  [1]=> string(1) "b"
  [2]=> string(1) "c"
}