为何每次执行Python脚本后文本文件大小翻倍？

核心问题出在文件指针的位置上：

• 用r+模式打开文件后，执行text.read()会把文件指针移到文件末尾。
• 虽然调用text.truncate(0)清空了文件，但指针并没有回到文件开头，仍然停在原来的末尾位置。
• 此时执行text.write(text_string)，会从指针所在位置开始写入内容，前面的空白区域会被填充空字节，导致文件大小变成「原文件长度 + 新内容长度」，看起来像是翻倍了。

另外你的脚本里还有几个语法错误，不修正会直接报错：

• list_to_delete里的""."多打了一个引号，应该改成"."
• special_characters_to_delete里的" :" "," :" "格式错误，要写成" ":" ", " ":" "
• list_to_delete里的空字符串""完全没必要，建议删掉，否则会做无意义的替换

修正后的两种写法 #

写法1：重置文件指针 #

在truncate(0)之后加上seek(0)，把指针移回文件开头再写入：

temp_letter_1 = temp_letter_2 = ""
with open("my_text_file.txt", "r+") as text:
    text_string = text.read()

    list_to_delete = ["\n","\"","'","«","»","(",".","!","?","^","&","*","_","`","%","#",",","–"]
    special_characters_to_delete = {"é":"e","è":"e","ê":"e","ë":"e","à":"a","ô":"o","î":"i","û":"u","œ":"oe","/":" ",":":" ",";":" ","-":" ","’":" ","   ":" ", "  ":" "}

    for i in list_to_delete:
        text_string = text_string.replace(i,"")

    for i in special_characters_to_delete:
        text_string = text_string.replace(i,special_characters_to_delete[i])

    text_string = text_string.lower()

    text.truncate(0)
    text.seek(0)  # 新增：将文件指针移到开头
    text.write(text_string)
print(text_string)

写法2：分开读写（更稳妥） #

先以只读模式读取内容，再用只写模式打开文件（w模式会自动清空原有内容），彻底避免指针问题：

temp_letter_1 = temp_letter_2 = ""
# 只读模式读取内容
with open("my_text_file.txt", "r") as text:
    text_string = text.read()

list_to_delete = ["\n","\"","'","«","»","(",".","!","?","^","&","*","_","`","%","#",",","–"]
special_characters_to_delete = {"é":"e","è":"e","ê":"e","ë":"e","à":"a","ô":"o","î":"i","û":"u","œ":"oe","/":" ",":":" ",";":" ","-":" ","’":" ","   ":" ", "  ":" "}

for i in list_to_delete:
    text_string = text_string.replace(i,"")

for i in special_characters_to_delete:
    text_string = text_string.replace(i,special_characters_to_delete[i])

text_string = text_string.lower()

# 只写模式写入，自动清空原有内容
with open("my_text_file.txt", "w") as text:
    text.write(text_string)
print(text_string)

内容的提问来源于stack exchange，提问作者Ramen Osaka