如何使用 Python 替换文本文件中的字符串？

Question

I am a newbie in programming and I'm trying to create a small text-based game with a high score feature. The game is fine, but I have a problem in trying to replace the highscore in the file if the player gets a higher score when the game is finished.

I created a function to make the file if it doesn't exist by using:

def createhighscore(): 
hs = os.listdir()
highscore = None 
if "highscore.txt" not in hs:
    highscore = open("highscore.txt", 'w')
    a = ["normal null 0\n", "expert null 0\n"]
    highscore.writelines(a)
return highscore

So now the highscore.txt file has two lines:

normal null 0
expert null 0

• normal/expert = the gamemode the player picked, i put the gamemode in the variable "mode"
• null = replaced with player name, i put the player name in the variable "player"
• 0 = replaced with the new highscore, i put the score in the variable "score"

I tried creating a code that split each word in each line into a list by using split(), and then checking if there is a condition where the score the player gets is higher than the current score for either mode. My code:

checkline = open("highscore.txt", "r+")
for line in checkline:
   x = line.split()
   if x[0] == mode.lower() and int(x[2]) < score:
       line.replace(x[1], player)
       line.replace(x[2], str(score))
       print("NEW HIGHSCORE")
checkline.close()

checkline = open("highscore.txt", "r+")
for line in checkline:
   x = line.split()
   if x[0] == mode.lower() and int(x[2]) < score:
       x[1] = player
       x[2] = score
       print("NEW HIGHSCORE")
checkline.close()

So if a player with the name "Raka" gets a score of 20 in Expert mode, the highscore.txt file should change to:

normal null 0
expert Raka 20

Sadly my code doesn't do anything and the content of the highscore.txt stays the same. I tried tweaking my code and until now I still haven't found the solution. I think my code does detect if the player gets a new highscore since "NEW HIGHSCORE" gets printed, but the text doesn't get replaced. I hope you guys can help me. Also, sorry for my bad English since it's not my first language. Thanks!

Answer 1

I made a simple script to write the changes in the highscores.txt, even if there are no changes the text file is overwritten.

score = 30
mode = "normal"
player = "Raka"

f = open("highscore.txt", "r")
lines = f.read().split("\n")
#remove empty lines in the lines list
lines = [line for line in lines if line.strip() != ""]
for x in range(0, len(lines)):
    words = lines[x].split(" ")
    if words[0] == mode and score > int(words[2]):
        lines[x] = mode +" "+player+" "+str(score)


#Write the changes in highscore.txt
outF = open("highscore.txt", "w")
for line in lines:
  outF.write(line)
  outF.write("\n")
outF.close()

Answer 2

Try using the following code:

check_high_score = open("highscore.txt", "r")
list_high_scores = check_high_score.readlines()
check_high_score.close()

to_write = []

for score in list_high_scores:
    if mode.lower() == "normal":
        if int(list_high_scores[0][2]) < score:
            to_write.append("normal " + player + " " + str(score))
        else:
            to_write.append(list_high_scores[0])
    elif mode.lower() == "expert":
        if int(list_high_scores[1][2]) < score:
            to_write.append("expert " + player + " " + str(score))
        else:
            to_write.append(list_high_scores[1])
        
write_score = open("highscore.txt", "w")
write_score.writelines(to_write)
write_score.close()

I'd recommend storing the data in a new variable after opening a file rather than directly accessing it, makes it easier to logic on it and improves the code readability. Also, try to use different variable names each time you make a file-handler. As to why your code is not working, I think it's because you haven't closed the file with checkline.close() after replacing the contents. Unless you close the file, the program will not push the data from the cache to the disk and the contents will remain the same. Alternatively, you can also use the flush ( checkline.flush() in your case) method to push the data into the file but keep in mind, in doing so, the file handler will keep running in the background and take memory while the close function will terminate it. Memory may not be a problem now but can be important in larger projects and it's good practice.