IndentationError：期望while循環中出現縮進的塊

Question

當我嘗試從多個網站抓取網頁時出現此錯誤

import urllib
urls = ["http://google.com","http://cnn.com"]

i=0
n=len(urls)

while i< n:
htmlfile = urllib.urlopen(urls[i])
htmltext =htmlfile.read()
print htmltext
i=i+1

錯誤 ：

  PS C:\python> python basic1.py
  File "basic1.py", line 9
  htmlfile = urllib.urlopen(urls[i])
  IndentationError: expected an indented block

Answer 1

import urllib 

urls = ["http://google.com","http://cnn.com"]

i=0
n=len(urls)

while i < n:
   htmlfile = urllib.urlopen(urls[i])
   htmltext =htmlfile.read()
   print htmltext
   i=i+1

Answer 2

您收到該錯誤是因為您沒有縮進。 Python需要嚴格縮進作為代碼塊分隔符。 嘗試這個：

i=0
n=len(urls)

while i< n:
    htmlfile = urllib.urlopen(urls[i])
    htmltext =htmlfile.read()
    print htmltext
    i=i+1

Answer 3

您有縮進錯誤，這意味着，您某些子塊之前需要具有4spaces，這在您的while代碼塊中很明顯，這是正確的方法：

import urllib
urls = ["http://google.com","http://cnn.com"]

i=0
n=len(urls)

while i< n:
    htmlfile = urllib.urlopen(urls[i])
    htmltext =htmlfile.read()
    print htmltext
    i=i+1