The four ancient brothers ranked from largest to smallest PHP simple array sorting implementation code

php Simple array sorting method for everyone to learn and reference.
PHP doesn’t know how to compare two arrays and needs to create a method to compare them.

1. Initialization of digital index array

Copy the code The code is as follows:

$arr = array('100', '200', '300');

The above code is created has an array containing 3 values. Numeric indexing of PHP arrays starts from 0. So the value of $arr[0] is 100.
You can use a simple "=" sign to copy the values ​​​​in one array to another array.
If you need to save the numbers in ascending order into an array, you can use the range() function to automatically create the array.

The following code will create an array of numbers from 1 to 10:

Copy the code The code is as follows:

$nums = range(1,10);

This function also has a third A parameter that can set the step size of digital growth. For example: range(1,10,2) is an odd number between 1 and 10.
PHP also supports related arrays, which can associate variable values ​​​​with keywords. For example:

Copy code The code is as follows:

$arr = array('one'=>100, 'two'=>200, 'three'=>300);

2. Array sorting

1. sort() function: Sort the array values ​​in ascending order of letters or numbers.
The sort() function is case-sensitive, all uppercase letters come before lowercase letters. This function also has a second parameter, which can be passed SORT_NUMERIC or SORT_STRING or SORT_REGULAR (default value). Specifying a sorting function is very useful. For example, when comparing the numbers 12 and 2, 12 is less than 2 from a string perspective, but the opposite is true from a numeric perspective.
2. asort() function, ksort() function:
If a related array is used, the ordering of keywords and values ​​must remain consistent after sorting. These two functions are needed. ksort is to sort by key (keyword), and asort is to sort by value (both in ascending order).
For example, there is an array:
$price = array('apple'=5,'banana'=6,'lychee'=7);
We use ksort($price); the result after sorting is: lychee--7, apple --5, banana--6
Use asort($price); the result after sorting is: apple--5, banana--6, lychee--7
The corresponding reverse sorting is to add in front of sort an 'r'. That is, rsort(), arsort(), krsort()

3. Sorting of multi-dimensional arrays

PHP knows how to compare two numbers or strings, but each element of a multi-dimensional array is an array.
PHP doesn’t know how to compare two arrays, so you need to create a method to compare them.

The above introduces the PHP simple array sorting implementation code of the four ancient brothers from large to small, including the content of the ancient four brothers ranking from large to small. I hope it will be helpful to friends who are interested in PHP tutorials.