stack.py
1 #!/usr/bin/env python
2 stack = []
3
4 def pushit():
5 stack.append(raw_input(' Enter New String: ').strip())
6
7 def popit():
8 if len(stack) == 0:
9 print 'Cannot pop from an empty stack!'
10 else:
11 print 'Removed [', `stack.pop()`, ']'
12
13 def viewstack():
14 print stack
15
16 CMDs = {'u': pushit, 'o':popit, 'v':viewstack}
17 def showmenu():
18
19 pr="""
20 P(U)sh
21 p(O)p
22 (V)iew
23 (Q)uit
24
25 Enter choice:"""
26 #注意下面第一个while和上面的pr对齐
27 while True:
28
29 while True:
30
31 try:
32
33 choice = raw_input(pr).strip()[0].lower()
34 except (EOFError, KeyboardInterrupt, IndexError):
35 choice = 'q'
36
37 print '\n You picked: [%s]' % choice
38 if choice not in 'uovq':
39
40 print 'Invalid option, try again'
41 else:
42 break
43
44 if choice == 'q':
45
46 break
47 CMDs[choice]()
48 if __name__ == '__main__':
49 showmenu()
NameError: name 'pr' is not defined
当出现此错误时，需注意的是将第一个while与上面的pr对齐。
