关于python：如何让raw_input重复直到我想退出？

How to let a raw_input repeat until I want to quit?

假设我想这样使用raw_input：

code = raw_input("Please enter your three-letter code or a blank line to quit:")

下：

1	if __name__=="__main__":

如何让它重复多次而不是每次运行程序时只重复一次？另一个问题是写什么代码可以满足条件"或者写一个空行退出(程序)"。

最好的：

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if __name__ == '__main__':
while True:
entered = raw_input("Please enter your three-letter code or leave a blank line to quit:")
if not entered: break
if len(entered) != 3:
print"%r is NOT three letters, it's %d" % (entered, len(entered))
continue
if not entered.isalpha():
print"%r are NOT all letters -- please enter exactly three letters, nothing else!"
continue
process(entered)

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while 1:
choice=raw_input("Enter:")
if choice in ["Q","q"]: break
print choice
#do something else

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def myInput():
return raw_input("Please enter your three-letter code or a blank line to quit:")

for code in iter(myInput,""):
if len(code) != 3 or not code.isalpha():
print 'invalid code'
continue
#do something with the code

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if __name__ == '__main__':

input = raw_input("Please enter your three-letter code or leave a blank line to quit:")
while input:
input = raw_input("Please enter your three-letter code or leave a blank line to quit:")