如何修复“列表索引超出范围”

Question

I have this index error: list index out of range

I have this problem on a VM with Security Onion installed on it. When I tried to use the code on PyCharm, it worked perfectly.

ip = []
mask = []

with open('program.txt') as file:
    for line in file:
        line_words = line.split()
        print(line_words[0])
        ip.append(line_words[0])
        mask.append(line_words[1])

ip = sorted(set(ip))

for i in range(len(ip)):
    x = "block any any -> " + ip[i] + " any " + mask[i]
    with open('final.txt', 'a') as file:
        file.write(x)
        file.write('\n')
        file.close()

I expect to have the output of the last print, but it goes with the error on the append line on the VM. I don't know how to make it work on this.

Answer 1

Your error came from the line_words[1] when the text in program.txt contain only one word.

Check before with a len(line_words) :

with open('program.txt') as file:
    for line in file:
        line_words = line.split()
        print(line_words[0])
        if len(line_words) >= 2:
            ip.append(line_words[0])
            mask.append(line_words[1])

Answer 2

Dorian already answered the if-statement solution. Alternatively, you can handle these errors with a try/except and print any occurring errors:

for line in file:
    line_words = line.split()
    print(line_words[0])
    try:
        ip.append(line_words[0])
        mask.append(line_words[1])
    except:
        print("The current line does not have enough words: {}".format(line_words)