php defines arrays
<?php
$array = [];
$array["key"] = "value";
?>Copy after login
There are two main ways to declare arrays in PHP:
Declare arrays using the array() function.
2. Directly assign values to array elements.
<?php
//array数组
$users = ['a','b','c','d'];
echo $users;//只会打印出数据类型Arra
print_r($users);//Array ( [0] => a[1] => b[2] => c[3] => d)
$numbers = range(1,5);//创建一个包含指定范围的数组
print_r($numbers);//Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 )
print_r(true);//1
var_dump(false);//bool(false)//print_r可以把字符串和数字简单地打印出来，数组会以Array开头并已键值形式表示，print_r输出布尔值和null的结果没有意义，因此用var_dump更合适Copy after login
//Display all the values in the array through loops
for($i = 0 ;$i < 5;$i++){
echo $users[$i];
echo '<br/>';
}Copy after login
//Use count/sizeof to count the number of units in the array or the number of attributes in the object
for($i = 0; $i < count($users);$i++){
echo $users[$i];
echo '<br/>';
}Copy after login
//You can also traverse the array through a foreach loop. The advantage is that you don’t need to consider the key
foreach($users as $value){
echo $value.'<br/>';//点号为字符串连接符号
}
//foreach循环遍历 $key => $value；$key和$value是变量名，可以自行设置
foreach($users as $key => $value){
echo $key.'<br/>';//输出键
}
?>Copy after login
Create an array with custom keys
Usage of
<?php
// 创建自定义的数组
$array = ["a"=>1,"b"=>2,"c"=>3,"d","e"];
//如果没有声明键，它会从零开始
print_r($array);//array([a]=>1,[b]=>2,[c]=>3,[0]=>d,[1]=>e);
?>Copy after login
each()
<?php
//通过为数组元素赋值来创建数组
$array['key'] = 22;
echo $array.'<br/>';//Array
//因为相关数组的索引不是数字，所以无法通过for循环来进行遍历操作，只能通过foreach循环或list()和each()结构
//each的使用
//each返回数组中当前的键/值对并将数组指针向前移动一步
$users = array('key'=>22,'key1'=>20,'key2'=>30);
//print_r(each($users));//Array ( [1] => 22 [value] => 22 [0] => array[key] => array)
//相当于：$a = array([0]=>array,[1]=>22,[value]=>22,[key]=>array);
$a = each($users);//each把原来的数组的第一个元素拿出来包装成新数组后赋值给$a
echo $a[0];//array //!!表示将真实存在的数据转换成布尔值
echo !!each($users);//1
?>Copy after login
## The pointer of each points to the first key-value pair and returns For the first array element, get its key-value pair and package it into a new array
Use of list()
list is used to use the array Assign values to some variables, see the following example:
<?php
$a = ['2','abc','def'];
list($var1,$var2) = $a;
echo $var1.'<br/>';//2
echo $var2;//abc
$a = ['name'=>'trigkit4','age'=>22,'0'=>'boy'];
//list只认识key为数字的索引
list($var1,$var2) = $a;
echo $var1;//boy
?>Copy after login
Note: list only recognizes indexes whose keys are numbers
Sorting of array elements
## Reverse sorting: sort(), asort() and ksort() are all forward Sorting, of course, also has a corresponding reverse sorting.
Implementation of reverse: rsort(), arsort() and krsort().
The array_unshift() function adds new elements to the head of the array, and the array_push() function adds each new element to the end of the array.
array_shift()删除数组头第一个元素,与其相反的函数是 array_pop(),删除并返回数组末 尾的一个元素。
array_rand()返回数组中的一个或多个键。
函数shuffle()将数组个元素进 行随机排序。
函数 array_reverse()给出一个原来数组的反向排序
数组的各类API的使用
注：count()和 sizeof()统计数组下标的个数
array_count_values()统计数组内下标值的个数
<?php
$numbers = array('100','2');
sort($numbers,SORT_STRING);//按字符串排序，字符串只比较第一位大小
print_r($numbers);//Array ( [0] => 100 [1] => 2 )
$arr = array('trigkit4','banner','10');
sort($arr,SORT_STRING);
print_r($arr);//Array ( [0] => 10 [1] => banner [2] => trigkit4 )
shuffle($arr);
print_r($arr);//随机排序
$array = array('a','b','c','d','0','1');
array_reverse($array);
print_r($array);//原数组的反向排序。 Array ( [0] => a [1] => b [2] => c [3] => d [4] => 0 [5] => 1 )
?>Copy after login
//数组的拷贝
$arr1 = array( '10' , 2);
$arr2 = &$arr1 ;
$arr2 [] = 4 ; // $arr2 被改变了,$arr1仍然是array('10', 3)
print_r($arr2);//Array ( [0] => 10 [1] => 2 [2] => 4 )Copy after login
//asort的使用
$arr3 = & $arr1 ;//现在arr1和arr3是一样的
$arr3 [] = '3' ;
asort($arr3);//对数组进行排序并保留原始关系
print_r($arr3);// Array ( [1] => 2 [2] => 3 [0] => 10 )
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//ksort的使用
$fruits = array('c'=>'banana','a'=>'apple','d'=>'orange');
ksort($fruits);
print_r($fruits);//Array ( [a] => apple [c] => banana [d] => orange )
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//unshift的使用
array_unshift($array,'z');//开头处添加一元素
print_r($array);//Array ( [0] => z [1] => a [2] => b [3] => c [4] => d [5] => 0 [6] => 1 )
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//current(pos)的使用
echo current($array);//z;获取当前数组中的当前单元
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//next的使用
echo next($array);//a;将数组中的内部指针向前移动一位
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//reset的使用
echo reset($array);//z;将数组内部指针指向第一个单元
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//prev的使用
echo next($array);//a;
echo prev($array);//z;倒回一位
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//sizeof的使用
echo sizeof($array);//7；统计数组元素的个数
//array_count_values
$num = array(10,20,30,10,20,1,0,10);//统计数组元素出现的次数
print_r(array_count_values($num));//Array ( [10] => 3 [20] => 2 [30] => 1 [1] => 1 [0] => 1 ) ?>Copy after login
urrent()：每个数组都有一个内部指针指向他的当前单元，初始指向插入到数组中的第一个元素
for循环遍历
<?php
$value = range(0,120,10);
for($i=0;$i<count($value);$i++){
print_r($value[$i].' ');//0 10 20 30 40 50 60 70 80 90 100 110 120
}?>Copy after login
数组的实例
array_pad函数的使用
<?php
//array_pad函数，数组数组首尾选择性追加
$num = array(1=>10,2=>20,3=>30);
$num = array_pad($num,4,40);
print_r($num);//Array ( [0] => 10 [1] => 20 [2] => 30 [3] => 40 )
$num = array_pad($num,-5,50);//array_pad(array,size,value)
print_r($num);//Array ( [0] => 50 [1] => 10 [2] => 20 [3] => 30 [4] => 40 )
?>Copy after login
size:指定的长度。整数则填补到右侧，负数则填补到左侧。
unset()的使用
<?php
//unset()的使用
$num = array_fill(0,5,rand(1,10));//rand(min,max)
print_r($num);//Array ( [0] => 8 [1] => 8 [2] => 8 [3] => 8 [4] => 8 )
echo '<br/>';
unset($num[3]);
print_r($num);//Array ( [0] => 8 [1] => 8 [2] => 8 [4] => 8 )
?>Copy after login
array_fill()的使用
<?php
//array_fill()的使用
$num = range('a','e');
$arrayFilled = array_fill(1,2,$num);//array_fill(start,number,value)
echo '<pre class="brush:php;toolbar:false">';
print_r($arrayFilled);
?>Copy after login
array_combine()的使用
<?php
$number = array(1,2,3,4,5);
$array = array("I","Am","A","PHP","er");
$newArray = array_combine($number,$array);
print_r($newArray);//Array ( [1] => I [2] => Am [3] => A [4] => PHP [5] => er )
?>Copy after login
array_splice()删除数组成员
<?php
$color = array("red", "green", "blue", "yellow");
count ($color); //得到4
array_splice($color,1,1); //删除第二个元素
print_r(count ($color)); //3
echo $color[2]; //yellow
echo $color[1]; //blue?>Copy after login
array_unique删除数组中的重复值
<?php
$color=array("red", "green", "blue", "yellow","blue","green");
$result = array_unique($color);
print_r($result);//Array ( [0] => red [1] => green [2] => blue [3] => yellow ) ?>Copy after login
array_flip()交换数组的键值和值
<?php
$array = array("red","blue","red","Black");
print_r($array);
echo "<br />";
$array = array_flip($array);//
print_r($array);//Array ( [red] => 2 [blue] => 1 [Black] => 3 ) ?>Copy after login
array_search()搜索数值
<meta charset="utf-8">
<?php
$array = array("red","blue","red","Black");
$result=array_search("red",$array)//array_search(value,array,strict)
if(($result === NULL)){
echo "不存在数值red";
}else{
echo "存在数值 $result";//存在数值 0
}
?>Copy after login
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