Python文件操作习题

以下是Python文件操作的练习题及其解答：

练习一：写一个程序在要保持文件内容的顺序不变的前提下，去除文件中重复的行。

import os

with open('db.txt', 'r', encoding='utf-8') as read_f, \
        open('db.txt.swap', 'w', encoding='utf-8') as write_f:
    s = set()
    for line in read_f:
        if line not in s:
            s.add(line)
            write_f.write(line)

os.remove('db.txt')
os.rename('db.txt.swap', 'db.txt')

练习二：写一个程序，将一个文件中的所有数字加总。

with open('numbers.txt', 'r') as f:
    total = 0
    for line in f:
        try:
            num = int(line.strip())
            total += num
        except ValueError:
            pass

print(total)

练习三：写一个程序，将一个文件中的所有单词按字母顺序排序后输出。

with open('words.txt', 'r') as f:
    words = []
    for line in f:
        words.extend(line.strip().split())

words.sort()
print(words)