Python文件大小写转换？

文件src.txt存储的是一篇英文文章， 将其中所有大写字母转换成小写字母存入文件dest.txt。

f = open('src.txt', 'r')
text = f.read()

lines = [line.lower() for line in text]
with open('dest.txt', 'w') as out:
    out.writelines(lines)

运行结果：

$ cat src.txt
f = OPEN('src.txt', 'r')
text = f.READ()

lines = [line.LOWER() FOR line IN text]
WITH OPEN('dest.txt', 'w') AS OUT:
    OUT.WRITELINES(lines)



$ python3 lower.py

$ cat dest.txt
f = open('src.txt', 'r')
text = f.read()

lines = [line.lower() for line in text]
with open('dest.txt', 'w') as out:
    out.writelines(lines)



$

如果用UNIX命令就很简单

 tr [:upper:] [:lower:] <src.txt >dest.txt