how to output every line in a file python

问题:

     if data.find('!masters') != -1:
         f = open('masters.txt')
         lines = f.readline()
         for line in lines:
               print lines
               sck.send('PRIVMSG ' + chan + " " + str(lines) + '\r\n')
               f.close()

masters.txt has a list of nicknames, how can I print every line from the file at once?. The code I have only prints the first nickname. Your help will be appreciate it. Thanks.

回答1:

Firstly, as @l33tnerd said, f.close should be outside the for loop.

Secondly, you are only calling readline once, before the loop. That only reads the first line. The trick is that in Python, files act as iterators, so you can iterate over the file without having to call any methods on it, and that will give you one line per iteration:

 if data.find('!masters') != -1:
     f = open('masters.txt')
     for line in f:
           print line,
           sck.send('PRIVMSG ' + chan + " " + line)
     f.close()

Finally, you were referring to the variable lines inside the loop; I assume you meant to refer to line.

Edit: Oh and you need to indent the contents of the if statement.

回答2:

You probably want something like:

if data.find('!masters') != -1:
     f = open('masters.txt')
     lines = f.read().splitlines()
     f.close()
     for line in lines:
         print line
         sck.send('PRIVMSG ' + chan + " " + str(line) + '\r\n')

Don't close it every iteration of the loop and print line instead of lines. Also use readlines to get all the lines.

EDIT removed my other answer - the other one in this discussion is a better alternative than what I had, so there's no reason to copy it.

Also stripped off the \n with read().splitlines()

回答3:

You could try this. It doesn't read all of f into memory at once (using the file object's iterator) and it closes the file when the code leaves the with block.

if data.find('!masters') != -1:
    with open('masters.txt', 'r') as f:
        for line in f:
            print line
            sck.send('PRIVMSG ' + chan + " " + line + '\r\n')

If you're using an older version of python (pre 2.6) you'll have to have

from __future__ import with_statement

回答4:

Loop through the file.

f = open("masters.txt")
lines = f.readlines()
for line in lines:
    print line

回答5:

Did you try

for line in open("masters", "r").readlines(): print line

?

readline() 

only reads "a line", on the other hand

readlines()

reads whole lines and gives you a list of all lines.