The functions to create an array are: 1. array(), which accepts a certain number of "key=>value" parameter pairs separated by commas as elements, the syntax is "array(key1=>value1,key2=> ;value2...);"; 2. array_fill(), will create an array by filling key values; 3. array_fill_keys(), will create an array by filling keys and values; 4. array_combine(), Arrays are created by merging arrays.
The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer
php provides a variety of functions to create arrays . Let’s find out below.
1. Use the array() function to create an array
The array() function can create a new array. It accepts a certain number of key=>value parameter pairs separated by commas. The syntax format is as follows:
$数组变量名 = array(key1 => value1, key2 => value2, ..., keyN => valueN);
The sample code is as follows:
<?php header("Content-type:text/html;charset=utf-8"); $array = array(0 => '红色', 1 => '黄色', 2 => '蓝色', 3 => '紫色'); echo '<pre class="brush:php;toolbar:false">'; var_dump($array); ?>
If you do not use the =>
symbol to specify the subscript, The default is an indexed array. The default index value also starts from 0 and increases in sequence. The sample code is as follows:
<?php header("Content-type:text/html;charset=utf-8"); $array = array('红色','黄色','蓝色', '紫色'); echo '<pre class="brush:php;toolbar:false">'; var_dump($array); ?>
The running results are the same as those of the previous example.
2. Use the array_fill() function to create an array by filling it
array_fill(): A new array will be created by filling the key value
<?php $arr=array_fill(0,4,"hello"); var_dump($arr); ?>
array_fill($index, $number, $value)
The function accepts 3 parameters that cannot be omitted$index
(starting index), $number
(number of padding elements), and $value
(key value used for padding).
Among them, the $index
parameter 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 $index
value and ends with the $index $number-1
value. For example, $index
is 2, $number
is 4, then the array index is: 2, 3, 4, 5.
If 0, the array index starts from 0
and ends with the $number-1
value. For example, $index
is 0, $number
is 4, then the array index is: 0, 1, 2, 3.
If it is negative, the array index is $index
, 0
, 1
, 2
, ..., $number-2
consists of. For example, $index
is -2, $number
is 4, then the array index is: -2, 0, 1, 2.
In the above example, the $index
of array_fill(0,4,"hello")
is 0 (the index starts from 0) , $number
is 4 (the array has four elements), so the array index is: 0, 1, 2, 3; and $value
is hello
, Then the key values of these four elements are hello
, so the output result is:
3. Use array_fill_keys() The function creates an array by filling it
array_fill_keys(): It will create a new array by filling the key name and key value
<?php $keys=array("a","b","c","d"); $arr=array_fill_keys($keys,"hello"); var_dump($arr); ?>
array_fill_keys($ keys,$value)
The function accepts two non-omitable parameters $keys
(an array containing the key name) and $value
(the key value is filled).
Simply put, the array_fill_keys() function will use the elements in the $keys
array as key names and $value
as 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:
##4. Use the array_combine() function to create an array in a merged manner When using the array_combine() function to create an array, the elements in the $keys array and $values array The number must be consistent so that the key name and key value can correspond one-to-one, otherwise an error will be reported and FALSE will be returned.
<?php header("Content-type:text/html;charset=utf-8"); $keys=array("a","b","c","d"); $values=array("red","green","blue","yellow"); var_dump($keys); var_dump($values); echo "使用array_combine()合并数组后:"; var_dump(array_combine($keys,$values)); ?>
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