PHP基础（一） 数组

/*
123456789123456789
123456789123456789
123456789123456789
123456789123456789
123456789123456789
123456789123456789
*/
//(按Alt可选多行，加内容……)

//参数默认值
function abc($a,$b,$c = 0){
    echo $a,$b,$c;
}
abc(1,3);

//可变参数
function def(){
    $arr = func_get_args();
    var_dump($arr);
}
echo "<pre>";
def(1,2,3,4,5,6);
echo "</pre>";

//数组定义
$arr1 = [];
$arr2 = array();
//索引数组
$arr1 =[1,2,3,"abc"];

//关联数组
$arr2 = [
    "one" => 1,
    "two" => 2,
    "three" =>3
 ];
echo $arr2["one"];

//数组方法
//推
array_push($arr2,"xyz");
//弹
array_pop($arr2);
//长度
count($arr2);
//判断数组中是否存在某个值
in_array("1",$arr2);
//数组合并
$arr3 = array_merge($arr1,$arr2);
//数组反转
$arr4 = array_reverse($arr2);
//数组去重
$str5 = array_unique($arr1);
//删除数组中的元素
unset($arr1[0]);
//重置
reset($arr1);

//echo "<pre>";
//var_dump($arr2);
//echo count($arr2);
//var_dump(in_array("111",$arr2));
//var_dump($arr5)

//echo "</pre>";

//数组遍历
//(先定义一波)
$arr6 = [1,2,3,4,5,6,7];
$arr7 = [
    "one"   => 1,
    "two"   => 2,
    "three" => 3,
    "four"  => 4
];
//1、for循环
echo "<br>";
for ($i = 0;$i <count($arr6);$i++){
    var_dump($arr6[$i]);
}

//2、foreach 遍历
foreach ($arr7 as $v){
    var_dump($v);
}
foreach ($arr7 as $key=>$value){
    echo $key;
    echo "______";
    echo $value;
    echo "<br>";
}

//指针遍历
echo "<pre>";
var_dump(each($arr7));
echo "</pre>";