php之数组
数组分类：
1.索引数组. 索引值从0开始，依次递增。
2.使用array()函数声明数组
<?php
// 1.直接为数组元素赋值即可声明数组
$contact_index[0] = 1;
$contact_index[1] = "高某";
$contact_index[2] = "A公司";
$contact_index[3] = "北京市";
$contact_index[] = "gao@a.com";
var_dump($contact_index);
$contact_key["ID"] = "2";
$contact_key["姓名"] = "峰某";
$contact_key["公司"] = "B公司";
$contact_key["邮箱"] = "feng@b.com";
var_dump($contact_key);
// 2.使用array()函数声明数组
$contact_key_array = array(
"ID" => 1;
"姓名" => "峰某";
"公司" => "B公司";
"邮箱" => "feng@b.com";
);
var_dump($contact_key_array);
?>
数组的遍历：
1.for语句遍历数组
2.foreach语句遍历数组
<?php
//用for语句遍历数组
$cars=array("Volvo","BMW","SAAB");
$arrlength=count($cars);
for($i=0;$i<$arrlength;$i++) {
echo $cars[$i];
echo "<br>";
}
?>
<?php
//foreach语句遍历关联数组
$age=array("Bill"=>"35","steve"=>"37","peter"=>"43");
foreach($age as $x=>$x_value) {
echo "Key=".$x.", Value=".$x_value;
echo "<br>";
}
?>
预定义数组
1.它就是一个特殊数组，操作方式没有区别。
2.不用声明它们，每个php脚本中默认存在。
3.它们在全局范围内自动生效。
预定义数组 说明
$_SERVER 变量由web服务器设定或者直接与当前脚本的执行环境相关联
$_ENV 执行环境提交至脚本的变量
$_GET 经由URL请求提交至脚本的变量
$_POST 经由HTTP POST 方法提交至标本的变量
$_REQUEST 经由GET,POST,COOKIE机制提交至脚本的变量
$_FILES 经由HTTP POST 文件上传而提交至脚本的变量
$_COOKIE 经由HTTP Cookie 方法提交至脚本的变量
$_SESSION 当前注册给脚本会话的变量
$_GLOBALS 包含一个引用指向每个当前脚本的全局范围内的有效的变量，该数组的键名 为全局变量的名称。
合并数组
array_merge()函数将数组合并到一起，返回一个联合的数组。
array array_merge(array array1 array2.....arrayN)
<?php
$fruits=array("apaple","banana","pear");
$numbered=array("1","2","3");
$cards=array_merge($fruits,$numbered);
print_r($cards);
// output
//Array ( [0] => apaple [1] => banana [2] => pear [3] => 1 [4] => 2 [5] => 3 )
?>
拆分数组
array_slice()函数将返回数组中的一部分，从键offset开始，到offset+length位置结束
array array_slice(array array,int offset,[int length])
offset 为正值时从前面开始，为负数时从后面开始
<?php
$fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon","Watermelon");
$subset=array_slice($fruits,3);
print_r($subset);
//output
//Array ( [0] => Pear [1] => Grape [2] => Lemon [3] => Watermelon )
?>
<?php
$fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon","Watermelon");
$subset=array_slice($fruits,2,-2);
print_r($subset);
//output
//Array ( [0] => Orange [1] => Pear [2] => Grape )
?>
数组头添加元素：
array_unshift函数在数组头添加元素
<?PHP
$fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon");
array_unshift($fruits,"AAAA","BBBB");
print_r($fruits);
//output
//Array ( [0] => AAAA [1] => BBBB [2] => Apple [3] => Banana [4] => Orange [5] => Pear [6] => Grape [7] => Lemon )
?>
数组头删除元素：
array_shift删除数组头元素
<?php
$fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon");
array_shift($fruits);
print_r($fruits);
//output
//Array ( [0] => Banana [1] => Orange [2] => Pear [3] => Grape [4] => Lemon )
?>
数组尾部添加元素：
array_push函数在数组尾部添加元素
<?php
$fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon");
array_push($fruits,"AAAA","BBBB");
print_r($fruits);
//output
//Array ( [0] => Apple [1] => Banana [2] => Orange [3] => Pear [4] => Grape [5] => Lemon [6] => AAAA [7] => BBBB )
?>
数组尾部删除元素：
array_pop函数删除数组尾部元素，返回的是数组的最后一个元素。
<?php
$fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon");
$result=array_pop($fruits);
print_r($result);
echo "<br>";
print_r($fruits);
//output
//$result 返回Lemon
//$fruits 返回Array ( [0] => Apple [1] => Banana [2] => Orange [3] => Pear [4] => Grape )
?>
