Python3-打印（readline（））返回空行

Question

I'm using the below code in an attempt to print 8 lines after a string that is found in the file result.txt. The script is definitely finding the string, but the print function returns 8 empty lines after the string is found, rather than the contents of the actual lines.

request = urllib.request.Request(websiteurl)
response = urllib.request.urlopen(request)
data = response.read()
fw = open('result1.txt', 'w')
fw.write(str(data))
fw.close()
with open('result1.txt', 'r') as f:
        for line in f:
                if 'DeMarco' in line:
                        for _ in range(8):
                                print (f.readline())

Answer 1

Your script is working, but you may add the parameter end='' in print function to avoid the automatically added end of line:

print (f.readline(), end='')

Are you sure about your file content? With 4 lines and this content file:

0
a DeMarco z
1
2
3
4
5
6
xDeMarcoPaul
A
B
DeMarco
C
D
E
F

And this script:

with open('result1.txt', 'r') as f:
  for line in f:
    if 'DeMarco' in line:
      for _ in range(4):
        print (f.readline(), end='')

I have this output:

1
2
3
4
A
B
DeMarco
C

But if in the 8 following lines, there is also a pattern DeMarco, it will not be detected because f.readline() moves the cursor.

Answer 2

Just read response result in tuples of lines. Your code should look like this:-

response = urllib.request.urlopen(websiteurl)
data = response.read()
fw = open('result1.txt', 'w')
fw.write(str(data))
fw.close()
lines = tuple(open('result1.txt', 'r'))
for x in lines:
    if 'google' in x:
        for y in range(8):
            print(x)