理解一下递归算法的流程

 

<?php
//test() 与 test1() 等价

Function Test() {
        static $count = 0;
        $count++;
        echo $count;
        if($count < 3){
                Test();
        }
        $count--;
}

Function Test1() {
        //------------1 begin---------------

        static $count = 0;
        $count++;
        echo $count; //1

        if($count < 3){
                //------------2 begin---------------

                static $count = 0;
                $count++;
                echo $count; //2

                if($count < 3){
                        //------------3 begin---------------

                        static $count = 0;
                        $count++;
                        echo $count; //3

                        if($count < 3){
                           echo "这里不可能执行.";
                        }
                        $count--;
                        //------------3 end---------------

                }
                $count--;
                //------------2 end---------------

        }
        $count--;
        //------------1 end---------------

}

?>