《python核心编程第二版》练习题——实现堆栈操作（FILO）

#!/usr/bin/env python
stack = []

def pushit():
stack.append(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 your choice:'''

while True:
while True:
try:
choice = input(pr).strip()[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()