而与raw_input创建无限循环

Question

In these lines:

foo = []

a = foo.append(raw_input('Type anything.\n'))
b = raw_input('Another questions? Y/N\n')

while b != 'N':
    b = foo.append(raw_input('Type and to continue, N for stop\n'))
    if b == 'N': break

print foo

How to do the loop break? Thanks!

Answer 1

list.append returns None.

a = raw_input('Type anything.\n')
foo = [a]
b = raw_input('Another questions? Y/N\n')

while b != 'N':
    b = raw_input('Type and to continue, N for stop\n')
    if b == 'N': break
    foo.append(b)

Answer 2

This is the way to do it

foo = []

a = raw_input('Type anything.\n')
foo.append(a)
b = raw_input('Another questions? Y/N\n')

while b != 'N':
    b = raw_input('Type and to continue, N for stop\n')
    if b == 'N': break
    foo.append(raw_input)

print foo

Answer 3

Just check for the last element added to foo :

while b != 'N':
    foo.append(raw_input('Type and to continue, N for stop\n'))
    if foo[-1] == 'N': break   # <---- Note foo[-1] here

Answer 4

You are assigning b to the result of a list append which is None. Even if you were lookking at foo, you would be looking at the list created by the foo.append and then comparing it to the charcter 'N'. Even if you only type N at the input, the value of foo would at least look like ['N']. You could eliminate b altogether with:

while True:
    foo.append(raw_input('Type and to continue, N for stop\n'))
    if 'N' in foo: break

Though this would leave the 'N' character in your list. Not sure if that is intended or not.