PHP array learning how to create arrays by filling

In the previous article "PHP Array Learning How to Create and Initialize a One-Dimensional Array (Detailed Code Explanation)", we introduced two conventional methods of creating an array: "Directly for the array Element assignment" and "array() function". Today we will talk about the creation of arrays and introduce two alternative methods of creating arrays. Let’s take a look.

In PHP, we can also create new arrays by filling. The main functions used are: array_fill() and array_fill_keys().

• array_fill(): will create a new array by filling the key value

• array_fill_keys(): will fill the key name and key Value method to create a new array

Let’s take a closer look at these two functions through code examples.

1. array_fill() function

array_fill($index, $number, $value)Function accepted 3 non-omitable parameters$index(starting index),$number(number of filling elements) and$value(key value used for filling) .

Among them, the$indexparameter supports negative values, and the array index has the following three values:

• If it is a positive number, the array The index starts from the$indexvalue and ends with the$index $number-1value. For example,$indexis 2,$numberis 4, then the array index is: 2, 3, 4, 5.

• If 0, the array index starts from0and ends with the$number-1value. For example,$indexis 0,$numberis 4, then the array index is: 0, 1, 2, 3.

• If it is negative, the array index is$index,0,1,2, ...,$number-2consists of. For example,$indexis -2,$numberis 4, then the array index is: -2, 0, 1, 2.

In the above example, the$indexofarray_fill(0,4,"hello")is 0 (the index starts from 0) ,$numberis 4 (the array has four elements), so the array index is: 0, 1, 2, 3; and$valueishello, Then the key values of these four elements arehello, so the output result is:

Looking at two examples:

Analysis: The index starts from 3 and ends at 3 4-1=6. The key values of the array are allhello, so the output result is:

The output result is:

$valueThe parameter can not only be asingle value/string, or it can bean array, then what is created is atwo-dimensional array.

The output result is:

2. array_fill_keys() function

array_fill_keys($keys,$value)The function accepts 2 parameters that cannot be omitted$keys(an array containing the fill key name),$value( populate the key value).

Simply put, the array_fill_keys() function will use the elements in the$keysarray as key names and$valueas values to fill a new array.

As can be seen from the above code example: the new array has four elements, and the key names are "a", "b", and "c##" #", "d"; the key values of these four elements are all "hello", so the output result is:

# #array_fill_keys() is the same as the array_fill() function. The

value can also accept an array, so what is created is atwo-dimensional array.