PHP数组相关函数

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1)array_count_values
        $array = array(1, "hello", 1, "world", "hello");
        $arr=array_count_values($array);//函数返回数组类型的数据
        print_r($array);//原来的数组不会受到任何影响
    2)array_key_exists
        $search_array = array('first' => 1, 'second' => 4);
        var_dump(array_key_exists('second',$search_array));
    3)array_search
        $array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red',4=>15);
        var_dump(array_search('15', $array,true));
    4)count
        $array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red',4=>15);
        var_dump(count($array));
    5)in_array
        $os = array("Mac", "NT", "Irix", "Linux");
        var_dump(in_array('Mac', $os));
    6)list
        $arr=array(60,80,100);
        list($sunshengli,$xiaohong,$xiaoming)=array(60,80,100);
        echo $sunshengli;
    7)asort
        $students=array(
            'sunshengli'=>60,
            'lilei'=>80,
            'hanmeimei'=>100,
            'zhangsan'=>90
        );
        asort($students);
        print_r($students);
        直接对数组里面的数据进行排序，第二个参数
            SORT_REGULAR - 正常比较单元（不改变类型） 
            SORT_NUMERIC - 单元被作为数字来比较 
            SORT_STRING - 单元被作为字符串来比较 
            SORT_LOCALE_STRING - 根据当前的区域（locale）设置来把单元当作字符串比较。
    8)array_filter
        function odd($var)
        {
            return($var % 2 == 1);
        }

        function even($var)
        {
            return($var % 2 == 0);
        }

        $array1 = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
        $array2 = array(6, 7, 8, 9, 10, 11, 12);

        echo "Odd :\n";
        print_r(array_filter($array1, "odd"));
        echo "Even:\n";
        print_r(array_filter($array2, "even"));

参考：PHP基础