使用 Python 以大写形式保存文本文件

Question

I'm trying to make the program that convert all words to uppercase.

a = open("file.txt",encoding='UTF-8')

for b in a:
    c = b.rstrip()
    print(c.upper())
a.close()

this is my code it prints uppercase text. But it can't save the file on 'file.txt'. I want to convert all words to uppercase.

How can I solve it????

Answer 1

Here's how you can do it: [provided that you are working with a small file]

Open the file in read mode store the uppercase text in a variable; then, open another file handler in write mode and write the content into it.

with open('file.txt' , 'r') as input:
    y = input.read().upper()
with open('file.txt', 'w') as out:
    out.write(y)

Answer 2

First convert the txt into the string:

with open('file.txt', 'r') as file:
    data = file.read()

And then revise the data to the uppercase:

data_revise = data.upper()

Finally revise the texts in the file:

fout = open('data/try.txt', 'w')
fout.write(data_revise)

Answer 3

You can actually do this "in place" by reading and writing a character at a time.

with open("file.txt", "r") as f:
    while (b := f.read(1)) != '':
        f.write(b.upper())

This is safe because you are processing the file one byte at a time (and writing one byte for every byte read) and not using seek to potentially overwrite a byte before it is read. The file-like object's underlying buffering and your system's disk cache means this isn't as inefficient as it looks.

(This does make one assumption: that the encoded length of b is always the same as b.upper() . I suspect that should always be true. If not, you should be able to read and write at least a line at a time, though not in place:

with open("input.txt") as inh, open("output.txt", "w") as outh:
    for line in inh:
        print(line.upper(), file=outh)

)

Answer 4

You can write all changes to temporary file and replace original after all data processed. You can use either map() or generator expression :

with open(r"C:\original.txt") as inp_f, open(r"C:\temp.txt", "w+") as out_f:
    out_f.writelines(map(str.upper, inp_f))

with open(r"C:\original.txt") as inp_f, open(r"C:\temp.txt", "w+") as out_f:
    out_f.writelines(s.upper() for s in inp_f)

To replace original file you can useshutil.move() :

import shutil
...
shutil.move(r"C:\temp.txt", r"C:\original.txt")