How to create an array in php and fill an array

In PHP and other programming language programming, the creation of arrays is often used. In front-end development, js array creation can be directly created and assigned by [] and new Array(). But what are the ways to create arrays in PHP? After reviewing the information and collecting and summarizing it online:

##1. Using array to create an array is the most common and convenient way:

$arr = array('a','b','c');
$arr[] = 'a' ; $arr[] = 'b' ; $arr[] = 'c';
$arr = array('name' => '关羽' , 'age' => 23 , 'sex' => '男')；

2. Sometimes you need to create a random array with a length of len, So you can use range():

Definition: array range(first, second, step) //first: minimum value of element second: maximum value of element step: element step size (the amount to be increased)

$number = range(0,5); 
print_r ($number); 

//打印：Array ( [0] => 0 [1] => 1 [2] => 2 [3] => 3 [4] => 4 [5] => 5 ) 

$number = range(0,50,10); 
print_r ($number); 

//打印：Array ( [0] => 0 [1] => 10 [2] => 20 [3] => 30 [4] => 40 [5] => 50 ) 

$letter = range("a","d"); 
print_r ($letter); 

//打印：Array ( [0] => a [1] => b [2] => c [3] => d )

3. Of course, under certain specific requirements, certain variables need to be stored in arrays. The variable names of these variables are converted into key names, and the variable values ​​are converted into key values. (Premise: the variable exists):

$firstname = "Peter"; 
$lastname = "Griffin"; 
$age = "38"; 
$result = compact("firstname", "lastname", "age"); 
print_r($result); 

//打印： Array ( [firstname] => Peter [lastname] => Griffin [age] => 38 ) 

$firstname = "Peter"; 
$lastname = "Griffin"; 
$age = "38"; 
$name = array("firstname", "lastname"); 
$result = compact($name, "location", "age"); 
print_r($result); 

//打印：Array ( [firstname] => Peter [lastname] => Griffin [age] => 38 ) 
//由于$location变量不存在，所以存入不了数组

4. Merge the two arrays into a new array. The value of the first array is the key name of the new array. The value in the second array is the key value of the new array:

Definition: The array_combine() function can combine two arrays into a new array. One of the arrays is the key name and the value of the other array. is the key value.

$a1=array("a","b","c","d"); 
$a2=array("Cat","Dog","Horse","Cow"); 
print_r(array_combine($a1,$a2)); 

//打印：Array ( [a] => Cat [b] => Dog [c] => Horse [d] => Cow )

5. Create an array with a fixed length as key value:

Definition: array_fill(start,number,value) //start: start Index number: the number of values ​​value: array value

$a=array_fill(2,3,"Dog"); 
print_r($a); 

//打印：Array ( [2] => Dog [3] => Dog [4] => Dog )

Related recommendations:

How to create an array in JavaScript?

10 recommended courses on creating arrays in PHP

How to use javascript to create arrays in batches

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