列表分配索引超出范围？

Question

I'm using the CSV module to update data via temporary files, it works until I try to create a new user. I have never experienced this error before and I have no understanding as to why it has occurred.

Data:

The scores file contains:

adam,0,5,4
bob,3,5,2
charlie,7,9,4
micheal,0,69,6

Code:

import csv
import os
from shutil import copyfile

name = input('Name: ')
score = int(input('Score: '))
found = False

open('temp9.csv','w').close()

with open('scores.csv','r') as data:
    read = csv.reader(data)
    for row in read:
        print(row)
        if row:
            if row[0] == name:
                found = True
                row[1] = row[2]
                row[2] = row[3]
                row[3] = score
                print('found')

            with open('temp9.csv','a') as temp:
                writer = csv.writer(temp)
                print('line =',[row[0],row[1],row[2],row[3]])
                writer.writerow([row[0],row[1],row[2],row[3]])

if found == False:
    with open('temp9.csv','a') as temp:
        row[0] = name
        row[1] = 0
        row[2] = 0
        row[3] = score

        writer = csv.writer(temp)
        print('line =',[row[0],row[1],row[2],row[3]])
        writer.writerow([row[0],row[1],row[2],row[3]])

os.remove('scores.csv')
copyfile('temp9.csv','scores.csv')

Error:

When I create a new user it creates the following error:

 Traceback (most recent call last): File "C:/Users/Adam/Desktop/foo.py", line 35, in <module> row[0] = name IndexError: list assignment index out of range 

Answer 1

You can greatly simplify (and correct) your loop like:

Code:

with open('temp9.csv','a') as temp:
    row = [name, 0, 0, score]

    writer = csv.writer(temp)
    print('line =', row)
    writer.writerow(row)

Lists:

This:

row[0] = name
row[1] = 0
row[2] = 0
row[3] = score

Does not work because you have not previously defined row as a list, so you cannot add to it in this way.

Also this:

print('line =',[row[0],row[1],row[2],row[3]])

misses the point of a list, in that the list does not need to be accessed via each element just to turn around and build the same list.