读取 python 上空文件的最后一行

Question

I have this function on my code that is supposed to read a files last line, and if there is no file create one. My issue is when it creates the files and tries to read the last line it comes up as an error.

with open(HIGH_SCORES_FILE_PATH, "w+") as file:
        last_line = file.readlines()[-1]
        if last_line == '\n':
            with open(HIGH_SCORES_FILE_PATH, 'a') as file:
                file.write('Jogo:')
                file.write('\n')
                file.write(str(0))
                file.write('\n') 

I have tried multiple ways of reading the last line but all of the ones I've tried ends in an error.

Answer 1

Opening a file in "w+" erases any content in the file. readlines() returns an empty list and trying to get value results in an IndexError . You can test for a file's existence with os.path.exists or os.path.isfile , or you could use an exception handler to deal with that case.

Start with last_line set to a sentinel value. If the open fails, or if no lines are read, last_line will not be updated and you can base file creation on that.

last_line = None
try:
    with open(HIGH_SCORES_FILE_PATH) as file:
        for last_line in file:
            pass 
except OSError:
    pass

if last_line is None:
    with open(HIGH_SCORES_FILE_PATH, "w") as file:
        file.write('Jogo:\n0\n')
    last_line = '0\n'