Detailed explanation of some functions of php

This article mainly shares with you the detailed explanation of some functions of PHP, mainly in the form of code. I hope it can help you.

1. array_diff_assoc($arr1,$arr2,$arr3...) function: compare the key names and key values ​​of two arrays and return the difference set

Example:

<?php
$a1=array("2"=>"this_2","3"=>"this_3","4"=>"this_4","5"=>"this_5");
$a2=array("1"=>"this_1","2"=>"this_2","3"=>"this_3");

$result1 = array_diff_assoc($a1,$a2); //数组可以交换顺序滴，也可以是多个数组
var_dump($result1);
?>

Print results:

array (size=2)
  4 => string 'this_4' (length=6)
  5 => string 'this_5' (length=6)

2. array_keys() function: Return a new array containing all the key names in the array

Example:

<?php
$a1=array("2"=>"this_2","3"=>"this_3","4"=>"this_4","5"=>"this_5");

$result2 = array_keys($a1);
var_dump($result2);
?>

Print Result:

array (size=4)
  0 => int 2
  1 => int 3
  2 => int 4
  3 => int 5

3. array_key_exists() function: Check whether the specified key name exists in an array. If the key name exists, it returns true. If the key name does not exist, it returns false.

Example:

<?php
$a1=array("2"=>"this_2","3"=>"this_3","4"=>"this_4","5"=>"this_5");

if (key_exists("2",$a1)){
	echo "yes!";
}else{
	echo "no!";
}
?>

Output result:

yes!

4. sort() function: Sort the array in ascending order

5. rsort() function: Sort the array in descending order

6. asort() function: Sort the associative array in ascending order according to the value

7. ksort() function: Sort the associative array in ascending order according to the key Sorting

8. arsort() function: Sort the associative array in descending order according to the value

9. krsort() function: Sort the associative array in descending order according to the key

10. count() function: returns the number of elements in the array

Example:

<?php
$a1=array("2"=>"this_2","3"=>"this_3","4"=>"this_4","5"=>"this_5");

$result3 = count($a1);
echo $result3;
?>

Output result:

4

Related recommendations:

Advanced explanation of php functions

Introduction to PHP function examples

Search performance test of php functions

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