Question

我的代码无法按照我的要求运行，我尝试对其进行评论以使其更容易。

基本上，我希望它最多尝试三次访问网站，如果成功，它将退出循环并继续，如果失败三次，它将退出该功能。

import random
import urllib2
import httplib
import urllib
import mechanize

def test():

    ## For three attempts...
    for i in range(0, 3):
        ## While in the three attempts...
        while True:
            ## Try...
            try:
                print "trying"
                ## Proxy list
                proxy_list = {"No Proxy": "None"}

                ## Randomly chosen proxy
                proxy_number = random.choice(proxy_list.keys())

                ## URL to post to in order to get data.
                post_url = ""

                browser = mechanize.Browser()
                browser.set_handle_robots(False)
                browser.addheaders = [('User-agent', 'Firefox')]
                parameters = {""}
                data = urllib.urlencode(parameters)

                ## If proxy_number = No Proxy then...
                if proxy_number == "No Proxy":
                    ## Do not setup proxy details
                    proxy_details = None
                ## If proxy_number is a real proxy then...
                else:
                    ## Get the proxy details
                    proxy_details = proxy_list[proxy_number]
                    ## Setup the proxy
                    browser.set_proxies({"http": proxy_number})

                ## Contact the webpage
                trans_array = browser.open(post_url).read().decode('UTF-8')
                print trans_array
                ## If successfully exit loop
                break
            ## On exceptions
            except:
                ## If unsuccessful continue and retry
                continue
            ## End the current loop
        break
            ## If it was unsuccessful after three attempts return false
        return

    print trans_array

test()

有谁能解释我做错了什么？

编辑：对于falsetru

def test():
    for i in range(3):
        try:
            ...
            break
    except:
        counter = counter  + 1
        print counter 
        continue

    if counter  == 3:
        return False

提前致谢 - Hyflex

Answer 1

如果发生错误，则执行continue;如果错误持续升高，while循环永远不会结束。

def test():
    for i in range(0, 3):
        while True:
            try:
                ...
                break
            except:
                continue # <---
        break

恕我直言，while循环是不必要的：

def test():
    for i in range(3):
        try:
            ...
            break
        except:
            continue
    else:
        return # Reach here if for loop was not ended by break
    print trans_array

不断循环，无法解决出错的问题

1 个答案: