python实现栈

　　由于python弱类型，因此免去了写泛型的麻烦。我定义一个stack类以栈的操作来维护一个list。

class stack:
    def __init__(self, _size = 1024):
        self.data = []
        self._size = _size
        self._top = -1

    def empty(self):
        if self._top == -1:
            return True
        else:
            return False

    def size(self):
        return self._top+1

    def top(self):
        return self.data[self._top]

    def clear(self):
        self.data = []
        self._top = -1

    def push(self, ele):
        if self._top + 1 == self._size:
            raise 'Stack Over Flow'
        else:
            self.data.append(ele)
            self._top += 1

    def pop(self):
        if self.empty():
            raise 'Stack Under Flow'
        else:
            ele = self.data[self._top]
            del self.data[self._top]
            self._top -= 1
            return ele

s = stack(5)

s.push(1)
s.push(2)
s.push(3)
s.push(5)
s.push(4)
# s.push(233)

size = s.size()
for i in range(0, size):
    print(s.top())
    s.pop()