函数调用函数

Question

The problem with this code is that if you input anything other than "bob" first, when you finally input "bob" , the main function will print None instead. Please run this code to fully understand what i'm having trouble with and to provide me some answers.

def main(name):
    print name

def x():
    name = raw_input()
    if name == "bob":
        return name
    else:
        print "error"
        x()

main(x())

Answer 1

Don't use recursion here. A simple while loop is sufficient.

def get_name_must_be_bob():
    while True:
        name = raw_input("Enter name: ")
        if name.lower() == "bob":   # "Bob", "BOB" also work...
            return name

        # `else` is not necessary, because the body of the `if` ended in `return`
        # (we can only get here if name is not Bob)

        print "Are you sure you're not Bob? Try again."

def main():
    name = get_name_must_be_bob()
    print "Hello, " + name


if __name__ == '__main__':
    main()

Answer 2

You do not return a value in the "error" case. Change the x() to return x()