21.文件操作(5)----常用案例

1.拷貝文件

src_file = input("請輸入原文件路徑:")
new_file = input("請輸入新文件路徑:")
with open(r"{}".format(src_file),mode="rb") as f1,\
    open(r"{}".format(new_file),mode="wb") as f2:
    while True:
        ret = f1.read(1024)       #一次讀取1024字節,防止內存溢出
        if not ret:
            break
        f2.write(ret)

2.修改文件

現在有一個a.txt文件,內容如下,要求將’哈哈哈’改爲呵呵呵

方法一:

with open("a.txt",mode="rt+",encoding="UTF-8") as f:
    f.seek(2,0)
    f.write("呵呵呵")     #會直接將原來的'哈哈哈'給覆蓋爲'呵呵呵'

方法二:

import os
with open("a.txt",mode="rt+",encoding="UTF-8") as f1,\
     open("r.txt",mode="wt",encoding="UTF-8") as f2:
    for line in f1:
        f2.write(line.replace("哈哈哈","呵呵呵"))
os.remove("a.txt")
os.rename("r.txt","a.txt")