當我運行該代碼我正在此錯誤

Question

class Queue(object): 
    def __init__(self): 
     self.items=[] 
    def enqueue(self,item): 
     self.items.insert(0,item) 

    def isempty(self): 
     return self.items==[] 
    def dequeue(self): 
     if not self.isempty(): 
      return self.items.pop() 
     else: 
      raise Exception('Queue is empty') 

    def size(self): 
     return len(self.items) 
    def peek(self): 
     if not self.isempty(): 
      return self.items[-1] 
     else: 
      raise Exception('Queue is empty') 

    def main(): 
     queue =Queue() 
     queue.enqueue(1) 
     queue.enqueue(2) 
     queue.enqueue(3) 
     print(queue.size()) 
     print(queue.peek()) 
     print(queue.dequeue()) 
     print(queue.peek()) 
    if __name__=='__main__': 
     main() 

＃ queue.peek（）＃當我使用的任何方法，它是表示本

Traceback (most recent call last): File "<pyshell#6>", line 1, in 
<module> 
    queue.peek() AttributeError: 'Queue' object has no attribute 'peek' 

Answer 1

它似乎是def main（）：並且行向前沒有正確縮進。

Answer 2

當格式正確和縮進，它工作正常：

class Queue: 

    def __init__(self): 
     self.items=[] 

    def enqueue(self, item): 
     self.items.insert(0, item) 

    def isempty(self): 
     return self.items==[] 

    def dequeue(self): 
     if not self.isempty(): 
      return self.items.pop() 
     else: 
      raise Exception('Queue is empty') 

    def size(self): 
     return len(self.items) 

    def peek(self): 
     if not self.isempty(): 
      return self.items[-1] 
     else: 
      raise Exception('Queue is empty') 


def main(): 
    queue =Queue() 
    queue.enqueue(1) 
    queue.enqueue(2) 
    queue.enqueue(3) 
    print(queue.size()) 
    print(queue.peek()) 
    print(queue.dequeue()) 
    print(queue.peek()) 

main()