python 递归返回None?

roffer 2015-02-05 10:25:31



city = ['四川','成都','温江']



def getWeatherForCity(city,city_code=''):

    if city_code == '':

        content = getContent('http://m.weather.com.cn/data5/city.xml')

        arr = content.split(',')

        for i in arr:

            if city[0] == i.split('|')[1]:

                city_code = i.split('|')[0]

                print city[0] + '的编码是：' + city_code

                del city[0]

                break

        getWeatherForCity(city,city_code)

    else:

        content = getContent('http://m.weather.com.cn/data5/city%s.xml' % city_code)

        arr = content.split(',')

        for i in arr:

            if city[0] == i.split('|')[1]:

                city_code = i.split('|')[0]

                print city[0] + '的编码是：' + city_code

                del city[0]

                break

        if city.__len__() > 0:

            getWeatherForCity(city,city_code)

        else:

            result = getContent('http://www.weather.com.cn/data/cityinfo/%s.html' % ('101' + city_code))

            print result

            return result

    

def getContent(url):

    return urllib2.urlopen(url).read()



print getWeatherForCity(city)

本人昨天刚学python，不知道哪里错了，求指教!

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DarkChampion 2015-02-06

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每个调用getWeatherForCity(city,city_code)的地方都改成

return getWeatherForCity(city,city_code)

递归返回上一层时结果没继续往上返回

panghuhu250 2015-02-06

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函数体里的(有几个)


        getWeatherForCity(city,city_code)

改成:


        return getWeatherForCity(city,city_code)

roffer 2015-02-05

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引用 3 楼 functionsub 的回复:

import urllib.request as urllib2     
        
city = ['四川','成都','温江']
 
def getWeatherForCity(city,city_code=''):
    if city_code == '':
        content = getContent('http://m.weather.com.cn/data5/city.xml')
        print(content)
        arr = content.split(',')
        for i in arr:
            if city[0] == i.split('|')[1]:
                city_code = i.split('|')[0]
                print(city[0] + '的编码是：' + city_code)
                del city[0]
                break
        getWeatherForCity(city,city_code)
    else:
        content = getContent('http://m.weather.com.cn/data5/city%s.xml' % city_code)
        arr = content.split(',')
        for i in arr:
            if city[0] == i.split('|')[1]:
                city_code = i.split('|')[0]
                print(city[0] + '的编码是：' + city_code)
                del city[0]
                break
        if city.__len__() > 0:
            getWeatherForCity(city,city_code)
        else:
            result = getContent('http://www.weather.com.cn/data/cityinfo/%s.html' % ('101' + city_code))
            print(result)
            return result
     
def getContent(url):
    return urllib2.urlopen(url).readall().decode('utf-8')
 
print(getWeatherForCity(city))

我的python是3.3，把read改成了readall，完了再decode一下，程序返回正常。。分别是 27，2701，270104

噢噢，不对，看错了，还是不德行。

roffer 2015-02-05

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引用 3 楼 functionsub 的回复:

import urllib.request as urllib2     
        
city = ['四川','成都','温江']
 
def getWeatherForCity(city,city_code=''):
    if city_code == '':
        content = getContent('http://m.weather.com.cn/data5/city.xml')
        print(content)
        arr = content.split(',')
        for i in arr:
            if city[0] == i.split('|')[1]:
                city_code = i.split('|')[0]
                print(city[0] + '的编码是：' + city_code)
                del city[0]
                break
        getWeatherForCity(city,city_code)
    else:
        content = getContent('http://m.weather.com.cn/data5/city%s.xml' % city_code)
        arr = content.split(',')
        for i in arr:
            if city[0] == i.split('|')[1]:
                city_code = i.split('|')[0]
                print(city[0] + '的编码是：' + city_code)
                del city[0]
                break
        if city.__len__() > 0:
            getWeatherForCity(city,city_code)
        else:
            result = getContent('http://www.weather.com.cn/data/cityinfo/%s.html' % ('101' + city_code))
            print(result)
            return result
     
def getContent(url):
    return urllib2.urlopen(url).readall().decode('utf-8')
 
print(getWeatherForCity(city))

我的python是3.3，把read改成了readall，完了再decode一下，程序返回正常。。分别是 27，2701，270104

感谢楼上，果然是decoude的原因(return result.decode('utf8'))，但是为什么呢？？？不解！

functionsub 2015-02-05

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import urllib.request as urllib2     
        
city = ['四川','成都','温江']
 
def getWeatherForCity(city,city_code=''):
    if city_code == '':
        content = getContent('http://m.weather.com.cn/data5/city.xml')
        print(content)
        arr = content.split(',')
        for i in arr:
            if city[0] == i.split('|')[1]:
                city_code = i.split('|')[0]
                print(city[0] + '的编码是：' + city_code)
                del city[0]
                break
        getWeatherForCity(city,city_code)
    else:
        content = getContent('http://m.weather.com.cn/data5/city%s.xml' % city_code)
        arr = content.split(',')
        for i in arr:
            if city[0] == i.split('|')[1]:
                city_code = i.split('|')[0]
                print(city[0] + '的编码是：' + city_code)
                del city[0]
                break
        if city.__len__() > 0:
            getWeatherForCity(city,city_code)
        else:
            result = getContent('http://www.weather.com.cn/data/cityinfo/%s.html' % ('101' + city_code))
            print(result)
            return result
     
def getContent(url):
    return urllib2.urlopen(url).readall().decode('utf-8')
 
print(getWeatherForCity(city))

我的python是3.3，把read改成了readall，完了再decode一下，程序返回正常。。分别是 27，2701，270104

roffer 2015-02-05