Detailed explanation of php array function example tutorial

$arr=array("name"=>"user1","age"=>"30","sex"=>"man") ;
foreach($arr as $key=>$val){
$keys[]=$key;
$vals[]=$val;
}
echo "";
print_r($keys );
echo "";
echo "";
echo "";
print_r($vals);
echo "";  p>
?>

2.Usage of array_values

$arr=array("name"=>"user1","age"=>"30","sex"=>"man");
$keys =array_values($arr);
echo "";
print_r($keys);
echo "";
?>

array_values(); //Get the value in the array array_keys();//Get the keys in the array in_array();//Check whether a value is in the array array_key_exists();//Check whether a key is in the array array_flip();//Swapping keys and values array_reverse();Reverse the values ​​in the array

Count the elements and uniqueness of arrays 1.count(); 2.array_count_values();//Count the number of occurrences of each value in the array. 3.array_unique();//Delete duplicates in the array Functions that use callback functions to process arrays:

1.array_filter();

$arr=array("user1"=>70,60,80,78,34,34,34,56,78,78);
function older($var) {
return ($var>60);
}
$arr2=array_filter($arr,"older");
echo "";
print_r($arr2);
echo " ";
?>

2.array_map(); Reference parameters: Requirement: Array value increases by 1

function show(&$arr){
foreach($arr as $key=>$val){
$arr[$key]=$val+1;
}
}

Sorting function of array 1.sort(); ascending order, key is not retained 2.rsort(); Descending order, key is not retained 3.asort(); ascending order, retain key 4.arsort(); Descending order, keep key 5.ksort(); Sort according to key in ascending order 6.krsort(); Sort by key in descending order 7.natsort(); natural number sorting in ascending order, such as the picture img2.jpg 8.natcasesort(); ignore case and sort in ascending order 9.multisort();Multiple array sorting ksort();

$arr=array("user1"=>10,"b"=>1,"c"=>3,"d"=>30);
 $arr2=array_flip($arr);
ksort($arr2);
echo "";
print_r($arr2);
echo "";
?>

natsort();

$array1 = $array2 = array("img12.png", "img10.png", "img2.png", "img1.png");
sort($array1) ;
echo "Standard sortingn";
print_r($array1);
natsort($array2);
echo "nNatural order sortingn";
print_r($array2);
?>

Most Group sorting:

$arr=array("aaa","bbbbbbbbb","cc","ddddd");
//Requirements:
//1. Sort by title length
// 2. The title length becomes the key of the title string
//Get the length of the value in the array and use it as a new array
//strlen($val) to get the length of the string
foreach ($arr as $val) {
$lens[]=strlen($val);
}
array_multisort($lens,SORT_ASC,$arr);//Sort the array, sort the second array according to the first array SORT_ASC means ascending order
 sort($lens);
$arr2=array_combine($lens, $arr);//The first array serves as the key corresponding to the second array, returning a new array
echo "";
print_r( $arr2);
echo "";
?>

Split, merge, decompose and combine functions 1.explode(); 2.inplode();//join(); 3.array_slice(); Array interception 4.array_splice(); Array cutting 5.array-merge(); merge multiple arrays 6.array_combine(); merge arrays, two arrays, the former array as key, the latter array as value 7.array_intersect(); Find the intersection of two arrays 8.array_diff(); Find the difference between two arrays, based on the first parameter 9.array_pop(); pops a value from the end and returns the pop-up value 10.array_push(); Push a value from the last position and return the number of elements 11.array_shift(); delete a value from the previous position 12.array_unshift(); Push a value from the front position

$str="php,js,html,ces,div";
$arr=explode(",",$str);
echo "";
 print_r($arr);
echo "";
?>

2.inplode(); Combine arrays into strings

$str="php,js,html,ces,div";
$arr=explode(",",$str);
$str2=implode ("-",$arr);
echo "";
print_r($str2);
echo "";
?>
< ;?php
$str="php,js,html,ces,div";
$arr=explode(",",$str);
$arr2=array_reverse($arr);//Talk about the values ​​in the array Perform reverse order
$str2=implode("-",$arr2);
echo "";
print_r($str2);
echo "";
?>
  p>

array_slice();

//Interception is always taken from back to front
$arr = array("aa","bb","cc","dd","ee","ff" ,"gg");
$arr2 = array_slice($arr, 0,2);//Indicates that 2 aa bbs are intercepted from the 0 position
$arr3 = array_slice($arr, -3,2);//Indicates Count from the back to the position of 3, start to intercept 2 //ee ff
echo "";
print_r($arr3);
echo "";
?>

Not only can it be removed and subtracted, but it can also be added

$arr = array("aa","bb","cc","dd","ee","ff","gg");
$arr2 = array_splice ($arr, 0, 3, array("hh","ii","jj","kk"));//Directly take the value of the original array and change the original array. The original array will be the value after removal The remaining values ​​
echo "";
print_r($arr2);
echo "";
echo "";
print_r($arr);
echo "< ;/pre>";
?>

array_merge();

$a = array("aa","bb","cc");
$b = array("dd","ee","ff","gg" );
$arr = array_merge($a, $b);
echo "";
print_r($arr);
echo "";
?>

Other useful array processing functions: 1.array_rand();//Randomly pick a key 2.range();//Get an array of a certain range 3.shuffle();//The function of disrupting the array 4.array_sum();//Calculate the sum of all people in the array (calculate the total score) If you calculate the key sum of an array, you can use array_flip() to swap the key sum values ​​of the array, and then calculate the key sum.

$arr = array("aa","bb","cc","dd","ee","ff","gg");
//Randomly shuffle the order of the original array
shuffle($arr);
//Get the first 3 items of the array
$arr2= array_slice($arr, 0, 3);
echo "";
 print_r($arr2);
echo "";
?>
//Randomly output four-character verification code implementation:
//Take out 1-9 a-z A-Z array
$a = range(1, 9);
$b = range(a, z);
$c = range(A, Z);
//Combine 3 arrays
$ d = array_merge($a,$b,$c);
//Shuffle the merged array
shuffle($d);
//Get the first 4 digits after the merge
$e = array_slice($d, 0, 4);
//Convert the $e array into a string
$f = join("", $e);
echo $f;
?>