PHP Lesson 7 Usage of Arrays 2_PHP Tutorial

PHP Lesson 7 Usage of Arrays 2

Learning Outline:

1. Understand array functions

2. Randomly output verification code

1. Array function:

Array function:
//Function: Provides a lot of very useful code snippets written by the official to improve writing speed.

1. Array key value operation function
2. Count the elements and uniqueness of the array
3. Functions that use callback functions to process arrays
4. Array sorting function
5. Split, merge, decompose and combine functions
6. Arrays and data structures
7. Other useful array processing functions


Array key value operation function:
1.array_values();

Simulate getting the values ​​of key and value

<?php
								$arr=array("name"=>"user1","age"=>"30","sex"=>"man");


								foreach($arr as $key=>$val){
									$keys[]=$key;
									$vals[]=$val;
								}
									
										echo "<pre class="code">";
										print_r($keys);
										echo "

"; echo "

---

"; echo "

";
								print_r($vals);
								echo "

"; ?>



2.Usage of array_values

<?php
					$arr=array("name"=>"user1","age"=>"30","sex"=>"man");


					$keys=array_values($arr);


					echo "<pre class="code">";
					print_r($keys);
					echo "

"; ?>


array_values();//Get the values ​​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(); //Key and value swap
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();

<?php
			$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 "<pre class="code">";
			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;


}


}




Array sorting function
1.sort(); Ascending order, key is not retained
2.rsort(); Descending order, key is not retained
3.asort(); Ascending order, keep 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();

<?php
		$arr=array("user1"=>10,"b"=>1,"c"=>3,"d"=>30);


		$arr2=array_flip($arr);


		ksort($arr2);


		echo "<pre class="code">";
		print_r($arr2);
		echo "

"; ?>



natsort();

<?php
		$array1 = $array2 = array("img12.png", "img10.png", "img2.png", "img1.png");


		sort($array1);
		echo "Standard sorting\n";
		print_r($array1);


		natsort($array2);
		echo "\nNatural order sorting\n";
		print_r($array2);
		?> 

Multi-array sorting:

<?php
		$arr=array("aaa","bbbbbbbbb","cc","ddddd");
		//需求:
		//1.按照标题长度排序
		//2.标题长度变成标题字符串的key


		//将数组中的value的长度取出,并作为一个新数组
		//strlen($val)取出字符串的长度
		foreach ($arr as  $val) {
			    $lens[]=strlen($val);
			}	


			
			array_multisort($lens,SORT_ASC,$arr);//对数组进行排序,根据第一个数组来排序第二个数组  SORT_ASC表示升序排序


			sort($lens);


			$arr2=array_combine($lens, $arr);//第一个数组作为第二个数组对应的key,返回一个新数组


			echo "<pre class="code">";
			print_r($arr2);
			echo "

"; ?>





Split, merge, decompose and combine functions
1.explode();
2.inplode();//join();
3.array_slice(); Array interception
4.array_splice(); Clipping of array
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 popup 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 position before washing
12.array_unshift(); Push a value from the front position

<?php


			$str="php,js,html,ces,div";
			$arr=explode(",",$str);


			echo "<pre class="code">";
			print_r($arr);
			echo "

"; ?>

2.inplode(); Combine arrays into strings

<?php


			$str="php,js,html,ces,div";
			$arr=explode(",",$str);


			$str2=implode("-",$arr);


			echo "<pre class="code">";
			print_r($str2);
			echo "

"; ?>

<?php


				$str="php,js,html,ces,div";
				$arr=explode(",",$str);


				$arr2=array_reverse($arr);//讲数组中的值进行倒序


				$str2=implode("-",$arr2);


				echo "<pre class="code">";
				print_r($str2);
				echo "

"; ?>




array_slice();

<?php
	
				//截取总是从后往前截取
			    $arr = array("aa","bb","cc","dd","ee","ff","gg");


			    $arr2 = array_slice($arr, 0,2);//表示从0的位置截取2个  aa bb
			    $arr3 = array_slice($arr, -3,2);//表示从后往前数到3的位置,开始截取2个//ee  ff


			    echo "<pre class="code">";
			     print_r($arr3);
			     echo "

"; ?>

不仅拆减,而且可以添加

<?php
		    $arr = array("aa","bb","cc","dd","ee","ff","gg");


		    $arr2 = array_splice($arr, 0, 3, array("hh","ii","jj","kk"));//直接取原数组的值,并将原数组进行改变,原数组为取走以后剩下的值


		    echo "<pre class="code">";
		    print_r($arr2);
		    echo "

"; echo "

";
		    print_r($arr);
		    echo "

"; ?> array_merge(); "; 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 shuffling 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 you can calculate the key sum.

<?php
	
	
    $arr = array("aa","bb","cc","dd","ee","ff","gg");


    //将原数组顺序随机打乱
    shuffle($arr);


    //取出数组的前3个
    $arr2= array_slice($arr, 0 , 3);


    echo "<pre class="code">";
    print_r($arr2);
    echo "

"; ?>





//Randomly output four characters verification code implementation:

<?php
	
	//取出1-9 a-z A-Z的数组
    $a = range(1, 9);
    $b = range(a, z);
    $c = range(A, Z);


    //将3个数组合并
    $d = array_merge($a,$b,$c);


    //将合并后的数组打乱
    shuffle($d);


    //取合并后的前4位
    $e = array_slice($d, 0, 4);


    //将$e数组变为字符串
    $f = join("", $e);


    echo $f;






	?>	

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