在 python 的文本文件中编辑特定行的一部分

Question

I'm trying to edit a text file. If my text has less than X lines, I want to add X-1 empty lines and then the line I want to add (for example a variable called my_addition). If the text has x or more lines, I need to edit them and add my_addition. Text for example:

text:text:text: * (X-1 lines)
my_addition:text:text: (line number X)

Answer 1

You could read the file as an array of lines and modify the last line, then write the modified lines back to the file.

with open("my_file.txt", "r") as f:     # Open the file in read mode
    lines = f.read().splitlines()       # Get lines as an array
    lines[-1] = "Hello" + lines[-1]     # Add your additon to the last line

with open("my_file.txt", "w") as f:     # open the file in write mode
    for line in lines:
        f.write("%s\n" % line)          # write each line to file