为什么程序不打印斐波那契数列?[副本]

我已经编写了两个版本的程序,并且是python的新手。我无法理解打印斐波那契数列时出错的原因。第一个程序正确打印斐波那契级数,但第二个程序有问题。请告诉我怎么了。

方案1

def fib(n):    # write Fibonacci series up to n
    """Print a Fibonacci series up to n."""
    a, b = 0, 1
    while a < n:
        print(a, end=' ')
        a, b = b, a+b
    print()

# Now call the function we just defined:
fib(2000)

输出

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597

方案2

# Let make a function that prints a Fibonacci 
def fib(n):    # write Fibonacci series up to n
    """Print a Fibonacci series up to n."""
    a = 0
    b = 1
    while a < n:
        print(a, end=" ")
        a = b
        b = a+b
fib(2000)

输出

0 1 2 4 8 16 32 64 128 256 512 1024