python实现堆栈 后进先出 LIFO

比较简单的数据结构，直接贴代码

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 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 (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()
参考自python核心编程 p145