Question

我看到了这个Flowchart，并决定用它制作一个程序。问题是，如果我第一次输入“no”，它只返回“Go Outside”。所有其他人都返回“无”。我正在使用Python 2.7

def waitawhile():
    print "Wait a while"
    rain2 = raw_input("Is it still raining?")
    if rain2.lower() == "no":
        return "Go Outside"
    elif rain2.lower() == "yes":
        waitawhile()
def Raining():
    print "Is it raining?"
    rain = raw_input()
    if rain.lower() == "no":
        return "Go Outside"
    elif rain.lower() == "yes":
        print "Have Umbrella?"
        umbrella = raw_input()
        if umbrella.lower == "yes":
            return "Go Outside"
        elif umbrella.lower() == "no":
            waitawhile()
print Raining()

Answer 1

问题在于您拨打waitawhile（来自Raining和waitawhile本身）。在调用之后，您将丢弃返回值并且不返回任何内容。要解决此问题，请更改以下来电：

waitawhile()

为：

return waitawhile()

确保对于这两个函数，如果不执行return语句，就无法到达函数的末尾。

Answer 2

你的程序有三个问题，下面它们已修复：

def waitawhile():
    print "Wait a while"
    rain2 = raw_input("Is it still raining?")
    if rain2.lower() == "no":
        return "Go Outside"
    elif rain2.lower() == "yes":
        return waitawhile()
def Raining():
    print "Is it raining?"
    rain = raw_input()
    if rain.lower() == "no":
        return "Go Outside"
    elif rain.lower() == "yes":
        print "Have Umbrella?"
        umbrella = raw_input()
        if umbrella.lower() == "yes":
            return "Go Outside"
        elif umbrella.lower() == "no":
            return waitawhile()
print Raining()

如下工作：

>>> ================================ RESTART ================================
>>> 
Is it raining?
yes
Have Umbrella?
yes
Go Outside
>>> ================================ RESTART ================================
>>> 
Is it raining?
yes
Have Umbrella?
no
Wait a while
Is it still raining?yes
Wait a while
Is it still raining?no
Go Outside
>>>

程序中的问题是逻辑错误，因此解释器不会显示语法错误：

您在if条件中使用了.lower而不是.lower()，它将始终为false。
您必须将waitawhile()方法返回print方法，否则会忽略select * from db_cat where cat_id='10' order by cast(order_no as int) asc方法的返回。

程序什么都没有

2 个答案: