php学习笔记------[数组的常用函数]

<?php
/* 数组的常用函数
 *
 *	数组的排序函数
 *	  sort()
 *	  rsort()
 *	  usort()
 *	  asort()
 *	  arsort()
 *	  uasort()
 *	  ksort()
 *	  krsort()
 *	  uksort()
 *	  uatsort()
 *	  natcasesort()
 *	  array_multisort()
 *
 *	   1.简单的数组排序
 *	     sort() rsort()
 *	   2.根据键名对数组排序
 *	     ksort() krsort()
 *	   3.根据元素的值对数组排序
 *	     asort() arsort()
 *	   4.根据"自然数排序“法对数组排序
 *	     natsort()//区分大小写字母比较 natcasescort()//不区分大小写字母的比较
 *	   5.根据用户自定义规则对数组排序
 *	     usort() uasort() uksort()对键排序
 *	   6.对维数组的排序
 *	     array_multisort()
 *
 *	拆分、合并、分解、接合的数组函数
 *	   1.array_slice()
 *	   2.array_splice()//删除
 *	   3.array_combine()//合并
 *	   4.array_merge();//合并
 *	   5.array_intersect();//多个数组的交集
 *	   6.array_diff();//返回多个数组的差集
 *
 *	数组与数据结构的函数
 *	  1.使用数组实现堆栈 //先进后出
 *	  	array_push() array_pop()
 *	  2.使用数组实现队列 //先进先出
 *	  	array_unshift() array_shift() unset()
 *
 *	
 *	其他与数组操作有关的函数
 *	   array_rand()
 *	   shuffle()
 *	   array_sum()
 *	   range()
 */

//简单数组排序的使用
$data=array(5,8,1,7,2);
sort($data);//元素由小到大进行排序
print_r($data);//Array ( [0] => 1 [1] => 2 [2] => 5 [3] => 7 [4] => 8 )
rsort($data);//元素由大到小进行排序
print_r($data);//Array ( [0] => 8 [1] => 7 [2] => 5 [3] => 2 [4] => 1 )

//根据键名排序的例子
$data_2=array(5=>"five",8=>"eight",1=>"one",7=>"seven",2=>"two");
ksort($data_2);//对数组的下标进行由小到大排序
print_r($data_2);//Array ( [1] => one [2] => two [5] => five [7] => seven [8] => eight )
krsort($data_2);//对数组的下标进行由大到小排序
print_r($data_2);//Array ( [8] => eight [7] => seven [5] => five [2] => two [1] => one )



//根据元素的值对数组排序
$data_3=array("1"=>"Linux","a"=>"Apache","m"=>"MySQL","l"=>"PHP");
//asort() arsort  与 sort() rsort()的区别在于 前者排序后保持原有的键名,后者不保持原有键名，且键名从0开始
asort($data_3);
print_r($data_3);//Array ( [a] => Apache [1] => Linux [m] => MySQL [l] => PHP )
echo '<br/>';
arsort($data_3);
print_r($data_3);//Array ( [l] => PHP [m] => MySQL [1] => Linux [a] => Apache )
echo '<br/>';
sort($data_3);
print_r($data_3);//Array ( [0] => Apache [1] => Linux [2] => MySQL [3] => PHP )
echo '<br/>';
rsort($data_3);
print_r($data_3);//Array ( [0] => PHP [1] => MySQL [2] => Linux [3] => Apache )

//根据”自然数排序法“对数组排序(0-9短者优先)
$data_4=array("file.txt","file11.txt","file2.txt","file22.txt");
sort($data_4);
print_r($data_4);//Array ( [0] => file.txt [1] => file11.txt [2] => file2.txt [3] => file22.txt )
echo '<br>';
natsort($data_4);
print_r($data_4);//Array ( [0] => file.txt [2] => file2.txt [1] => file11.txt [3] => file22.txt )
echo '<br>';
natcasesort($data_4);
print_r($data_4);//Array ( [0] => file.txt [2] => file2.txt [1] => file11.txt [3] => file22.txt )
echo '<br>';

//用户自定义排序函数
echo '<br/>';
$data_5=array("Linux","Apache","MySQL","PHP");
usort($data_5,"sortbylen");//通过元素长度排序
print_r($data_5);//Array ( [0] => PHP [1] => MySQL [2] => Linux [3] => Apache )
function sortbylen($one,$two){
	if(strlen($one)==strlen($two))
		return 0;
	else
		return (strlen($one)>strlen($two))?1:-1;
}

//拆分、合并、分解、接合的数组函数
echo '<br/>';
$data_6=array("Linux","Apache","MySQL","PHP");
print_r(array_slice($data_6,1,2));//取下标为1、2的元素
//Array ( [0] => Apache [1] => MySQL ) 下标重置从0开始
echo '<br/>';

print_r(array_slice($data_6,-2,1));//从后边的第二个开始取返回一个，不是从0开始的
//Array ( [0] => MySQL ) 下标重置从0开始
echo '<br/>';

print_r(array_slice($data_6,1,2,true));
//Array ( [1] => Apache [2] => MySQL )  保留原有的下标

echo '<br/>';


//array_combine()
$a1=array("OS","WebServer","DataBase","Language");
$a2=array("Linux","Apache","MySQL","PHP");

print_r(array_combine($a1,$a2));//第一个参数作为键名，第二个作为值来合并
//Array ( [OS] => Linux [WebServer] => Apache [DataBase] => MySQL [Language] => PHP ) 

echo '<br/>';

//array_merge()
$a3=array("OS","WebServer","DataBase","Language");
$a4=array("Linux","Apache","MySQL","PHP");
$a5=$a3+$a4;
print_r($a5);//因为两个数组下标重复所以显示这样
//Array ( [0] => OS [1] => WebServer [2] => DataBase [3] => Language )
echo '<br/>';
print_r(array_merge($a3,$a4));//合并并重新索引
//Array ( [0] => OS [1] => WebServer [2] => DataBase [3] => Language [4] => Linux [5] => Apache [6] => MySQL [7] => PHP ) 

echo '<br/>';

//array_intersect()
$a7=array("OS","WebServer","DataBase","Language",1,2,3);
$a8=array("Linux","Apache","MySQL","PHP",2,3,4);
print_r(array_intersect($a7,$a8));//Array ( [5] => 2 [6] => 3 )
echo '<br/>';

//array_diff()
$a9=array(1,2,3,4);
$a10=array(3,4,5,6);
print_r(array_diff($a9,$a10));//Array ( [0] => 1 [1] => 2 ) 
//返回第一个数组跟第二个相差的元素
echo '<br/>';


//使用数组实现堆栈
$b=array(1,2,3,4);
$b[]="a";//入栈
array_push($b,"b","c");//使用函数入栈
print_r($b);//Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => a [5] => b [6] => c )
echo '<br/>';

$value=array_pop($b);//使用函数出栈
print_r($b);//Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => a [5] => b )
echo '<br/>';
echo $value;//显示出栈的元素的值 c
echo '<br/>';

//使用数组实现队列
$c=array(1,2,3);
print_r($c);//Array ( [0] => 1 [1] => 2 [2] => 3 )
echo '<br/>';
array_unshift($c,"abc","bcd");//入队
print_r($c);//Array ( [0] => abc [1] => bcd [2] => 1 [3] => 2 [4] => 3 ) 
echo '<br/>';
$values=array_shift($c);//出队
print_r($c);// Array ( [0] => bcd [1] => 1 [2] => 2 [3] => 3 )
echo '<br/>';
unset($c[2]);//删除指定位置元素
print_r($c);//Array ( [0] => bcd [1] => 1 [3] => 3 )
echo '<br/>';


//array_rand()  随机返回数组下标
$arr=array(1,3,4,5,76,7,99,6,2,3);
echo array_rand($arr);//返回的是随机的数组元素的下标
echo $arr[array_rand($arr)];//随机显示数组元素的值
echo '<br/>';
//shuffle()  随机重新排列数组
$arr2=array(32,35,33);
shuffle($arr2);
print_r($arr2);//数组元素位置随机变换
echo '<br/>';
//array_sum()  求和
$arr3=array(1,3,5);
echo array_sum($arr3); //返回9
echo '<br/>';
print_r($arr3);//Array ( [0] => 1 [1] => 3 [2] => 5 )
echo '<br/>';
//range(最小值，最大值，步长)
$arr4=range(0,100,10);
print_r($arr4);//Array ( [0] => 0 [1] => 10 [2] => 20 [3] => 30 [4] => 40 [5] => 50 [6] => 60 [7] => 70 [8] => 80 [9] => 90 [10] => 100 ) 

?>