python程序设计

1、修改用户登录系统

2、栈功能的显示

两者二选一提交运行过程和结果。功能要求如下图：

多加注释

class Stack(object):
    """栈"""
    def __init__(self):
        self.items = []
 
    def is_empty(self):
        return self.items == []
 
    def push(self, item):
        self.items.append(item)
     
    def pop(self):
        return self.items.pop()
 
    def peek(self):
        return self.items[len(self.items)-1]
 
    def size(self):
        return len(self.items)
    def display(self):
        print(self.items)

if __name__ == "__main__":
    stack = Stack()
    while True:
        print("1.入栈")
        print("2.出栈")
        print("3.查看栈顶元素")
        print("4.查看栈长度")
        print("5.查看栈中元素")
        print("6.退出")
        str = input("请选择操作：")
        if str == '1':
            s = input("请输入入栈元素：")
            stack.push(s)
        elif str == '2':
            if stack.is_empty():
                print("栈为空")
            else:
                print("出栈元素：" + stack.pop())
        elif str == '3':
            if stack.is_empty():
                print("栈为空")
            else:
                print("栈顶元素："+ stack.peak())
        elif str == '4':
            print("栈长度：%d "% stack.size())
        elif str == '5':
            print("栈中元素：")
            stack.display()
        elif str== '6':
            print("程序结束！")
            break
        else:
            print("选择有误，请重新输入！")

栈的操作，运行结果：

代码如下：

class Stack(object):
    """栈"""
    def __init__(self):
        self.items = []

    def is_empty(self):
        """判断栈是否为空"""
        return self.items ==[]

    def push(self, item):
        """入栈"""
        self.items.append(item)

    def pop(self):
        """出栈"""
        return self.items.pop()

    def peak(self):
        """获取栈顶元素"""
        return self.items[len(self.items)-1]

    def size(self):
        """获取栈的长度"""
        return len(self.items)

    def display(self):
        """显示栈内元素"""
        print(self.items)


if __name__ == "__main__":
    stack = Stack()
    flag = True
    while flag:
        print("1.入栈")
        print("2.出栈")
        print("3.查看栈顶元素")
        print("4.查看栈长度")
        print("5.查看栈中元素")
        print("6.退出")

        val = int(input("请选择操作："))

        if val == 1:
            s = input("请输入入栈元素：")
            stack.push(s)
        elif val == 2:
            if stack.is_empty():
                print("栈为空")
            else:
                print("出栈元素：" + stack.pop())
        elif val == 3:
            if stack.is_empty():
                print("栈为空")
            else:
                print("栈顶元素："+ stack.peak())
        elif val == 4:
            print("栈长度：%d" %stack.size())
        elif val == 5:
            print("栈中元素：")
            stack.display()
        else:
            flag = False

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