Python 用列表模拟堆栈 stack.py

'''
Created on 2011-7-23

@author: Administrator
'''
#!/usr/bin/env python

stack=[]

def pushit():
    stack.append(raw_input('Enter New string :').strip())

def popit():
    if len(stack)==0:
        print 'Cannot pop from an empty stack !'
    else:
        print 'Removed  [' , `stack.pop()` , '] '

def viewstack():
    print stack

CMDs={'u':pushit,'o':popit,'v':viewstack}

def showmenu():
    pr="""
p(U)sh
P(O)P
(V)iew
(Q)uit
Enter choice:"""
    while True:
        while True:
            try:
                choice=raw_input(pr).strip()[0].lower()
            except:
                choice='q'
            print '\n You pickde: [%s]' %choice
            if choice not in 'uovq':
                print 'Invalid option ,try again'
            else:
                break
        if choice =='q':
            break
        CMDs[choice]()
if __name__== '__main__' :
    showmenu()