PHP堆栈实现 [英] PHP Stack Implementation

问题描述

我想构建一个在PHP中实现的堆栈。最初我有这个代码：

  class Stack 
 {
 protected $ stack; 
 protected $ limit; 
 
 public function __construct（$ limit = 10）{
 //初始化栈
 $ this-> stack = array（）; 
 // stack只能包含这么多项目
 $ this-> limit = $ limit; 
} 
 
 public function push（$ item）{
 //堆栈溢出陷阱
 if（count（$ this-> stack）< $ this - > limit）{
 //将数组前面的项添加到数组的开头
 array_unshift（$ this-> stack，$ item）; 
} else {
抛出新的RunTimeException（'Stack is full！'）; 
} 
} 
 
 public function pop（）{
 if（$ this-> isEmpty（））{
 // trap for stack underflow 
抛出新的RunTimeException（'Stack is empty！'）; 
} else {
 //从数组开头的pop项
 return array_shift（$ this-> stack）; 
} 
} 
 
 public function top（）{
 return current（$ this-> stack）; 
} 
 
 public function isEmpty（）{
 return empty（$ this-> stack）; 
} 
} 
  

正常初始化类 使用这个：

  $ stack = new Stack（）; 
 $ stack-> push（1）; 
 $ stack-> push（2）; 
 $ stack-> push（3）; 
 $ stack-> push（4）; 
 $ stack-> push（5）; 
  

这是正确的，正在运行。但是，我想初始化一个初始值，如下所示：

  $ stack = new Stack（array（1,2 ，3,4,5））; 
  

如何实现？

---

请注意，所有其他功能（例如弹出和推送）都可以正常工作。

解决方案

这是正确的堆栈类的实现。要正确地将数组初始化为堆栈的值，您必须按照以下方式反转该数组的值：

  class Stack 
 {
 protected $ stack; 
 protected $ limit; 
 
 public function __construct（$ values = array（），$ limit = 10）{
 //初始化栈
 $ this-> stack = array_reverse（$ values） ; 
 // stack只能包含这么多项目
 $ this-> limit = $ limit; 
} 
 
 public function push（$ item）{
 //堆栈溢出陷阱
 if（count（$ this-> stack）< $ this - > limit）{
 //将数组前面的项添加到数组的开头
 array_unshift（$ this-> stack，$ item）; 
} else {
抛出新的RunTimeException（'Stack is full！'）; 
} 
} 
 
 public function pop（）{
 if（$ this-> isEmpty（））{
 // trap for stack underflow 
抛出新的RunTimeException（'Stack is empty！'）; 
} else {
 //从数组开头的pop项
 return array_shift（$ this-> stack）; 
} 
} 
 
 public function top（）{
 return current（$ this-> stack）; 
} 
 
 public function isEmpty（）{
 return empty（$ this-> stack）; 
} 
} 
  

快乐编码！

I want to construct a stack implemented in PHP. Initially I have this code:

class Stack
{
    protected $stack;
    protected $limit;

    public function __construct($limit = 10) {
        // initialize the stack
        $this->stack = array();
        // stack can only contain this many items
        $this->limit = $limit;
    }

    public function push($item) {
        // trap for stack overflow
        if (count($this->stack) < $this->limit) {
            // prepend item to the start of the array
            array_unshift($this->stack, $item);
        } else {
            throw new RunTimeException('Stack is full!');
        }
    }

    public function pop() {
        if ($this->isEmpty()) {
            // trap for stack underflow
          throw new RunTimeException('Stack is empty!');
      } else {
            // pop item from the start of the array
            return array_shift($this->stack);
        }
    }

    public function top() {
        return current($this->stack);
    }

    public function isEmpty() {
        return empty($this->stack);
    }
}

And initialize the class normally using this:

$stack = new Stack();
$stack->push(1);
$stack->push(2);
$stack->push(3);
$stack->push(4);
$stack->push(5);

This is correct and running. However, I want to initialize my stack with an initial value like this:

$stack = new Stack(array(1,2,3,4,5));

How can I implement this?

---

Note that all other functions (e.g pop and push) are functional.

解决方案

Here's the implementation of the correct stack class. To correctly initialize array to the value of a stack, you have to reverse the values of that array like this:

class Stack
{
    protected $stack;
    protected $limit;

    public function __construct($values = array(),$limit = 10) {
        // initialize the stack
        $this->stack = array_reverse($values);
        // stack can only contain this many items
        $this->limit = $limit;
    }

    public function push($item) {
        // trap for stack overflow
        if (count($this->stack) < $this->limit) {
            // prepend item to the start of the array
            array_unshift($this->stack, $item);
        } else {
            throw new RunTimeException('Stack is full!');
        }
    }

    public function pop() {
        if ($this->isEmpty()) {
            // trap for stack underflow
          throw new RunTimeException('Stack is empty!');
      } else {
            // pop item from the start of the array
            return array_shift($this->stack);
        }
    }

    public function top() {
        return current($this->stack);
    }

    public function isEmpty() {
        return empty($this->stack);
    }
}

Happy coding!

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