我在Python中的嵌套循环有什么问题？

Question

如何在Python(3.0版)中创建嵌套循环？

我想尝试以下循环向我展示两个数字的产品:

def PrintProductsBelowNumber(number):
    number1 = 1
    number2 = 1
    while number1 <= number:
        while number2 <= number:
            print(number1, "*", number2, "=", number1 * number2)
            number2 += 1
        number1 += 1

PrintProductsBelowNumber(2)

结果我得到:

1 * 1 = 1
1 * 2 = 2

所以看起来number1上的外部循环不会运行.

如何使number1循环运行,从而获得:

1 * 1 = 1
1 * 2 = 2
2 * 1 = 2
2 * 2 = 4

Answer 1

number2只有初始化一次,你需要为内循环的每次迭代重新初始化它.但是,这段代码非常类似C而且不是非常Pythonic.更好的方法是使用for number in range(n)构造:

def PrintProductsBelowNumber(number):
    for number1 in range(1, number+1):
        for number2 in range(1, number+1):
            print(number1, "*", number2, "=", number1 * number2)

Answer 2

因为在内部循环第一次完成后,您没有将number2设置回1.number1然后递增,但由于number2仍然太高,内部循环不会再次运行.

def PrintProductsBelowNumber(number):
    number1 = 1
    while number1 <= number:
        number2 = 1
        while number2 <= number:
            print(number1, "*", number2, "=", number1 * number2)
            number2 += 1
        number1 += 1

PrintProductsBelowNumber(2)

编辑:亚当的解决方案总的来说要好得多,但这是为了说明为什么你的工作方式不像你认为的那样.