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Python 使用list實現簡單的堆疊

#! /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).strop()[0].lower()
            except (EOFError, KeyboardInterrupt, IndexError):
                choice = 'q'

            print '\nYou picked: [%s]' % choice
            if choice not in 'uovq':
                print 'Invalid option, try again!'
            else:
                break

        if choice == 'q':
            break

        CMDs[choice]()

if __name__ == '__main__':
    showmenu()