persistent_game.py

#!/usr/bin/env python
""" Simple example of a Python program that initializes and saves a persistent 'high score' variable
    by reading/writing a value to a file. """

high_score_file_name  = "hiscore"

try:
    with open(high_score_file_name, "r") as f: #open the file 'hiscore' in read mode
        old_score = int(f.read())

except FileNotFoundError:                                  # if the 'hiscore' file does not exist... (e.g., no one has played the game yet)
    old_score = 0                                          # initialize the old_score variable to default value (e.g., 0)...
    print(f"File 'hiscore' not found. Creating it now...") # open the file 'hiscore' in write mode...
    with open(high_score_file_name, "w") as f:
        f.write(str(old_score))                            #...and write it to the file. (not strictly necessary yet, but at this point we could now open
                                                           # the 'hiscore' file in this directory and examine its contents. It should now read '0'

new_score = int(input("Enter a number: "))                 # our 'game' consists of accepting a numeric input from a player...

hi_score = max(new_score, old_score)                       # and setting the 'high score' variable to the highest value entered by any player of the game 

with open(high_score_file_name, "w") as f:                 # finally, before exiting the program... open the 'hiscore' file in write mode...
    f.write(str(hi_score))                                 # write the `hi_score` variable to a file (be sure to cast to string first -- our file descriptor object `f` expects an str type when opened in "w" mode)
    print(f"The highest number is now: {hi_score}")        # and print the new high score to the user.