Question

#!/usr/bin/python

import os,sys
from os import path

input = open('/home/XXXXXX/ERR001268_1', 'r').read().split('\n')

at = 1
for lines in range(0, len(input)):
    line1 = input[lines]
    line4 = input[lines+3]
    num1 = line1.split(':')[4].split()[0]
    num4 = line4.split(':')[4].split()[0]
    print num1,num4


    at += 1

However I got the error: list index out of range

What’s the problem here?

btw, besides "at +=1", is there any other way to finish this cycle loop?
thx

Answer 1

Lets say len(input) == 10. range(0, len(input)) iterates [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]. And when lines > 6 and you’re trying to access input[lines+3], it clearly an IndexError, because there is no index[10], [11] etc .

And line1.split(':')[4] can also raise an IndexError if line1.count(":") < 4.

I didn’t understand the last at part, it seems not doing anything, but you can break the loop easily with break statement.

Also, naming a variable input is a bad idea because it conflicts with builtin input function. And range(0, len(input)) == range(len(input)), so 0 as range’s first argument is unnecessary.