一.占内存式
f = open("user.txt","r",encoding="utf-8") data = "" old_str = "张三" new_str = "李四" for line in f: if old_str in line: #此处用in判断更好,如果用"=="的话,原文中若存在 时,if判断不会执行 line = line.replace(old_str,new_str) data += line f = open("user.txt","w",encoding="utf-8") f.write(data)
此方法从文件中把文件内容读取出来,放到内存里修改,修改完毕后再覆盖原文件起到修改的作用
二.占硬盘式
old_str = "张三"
new_str = "李四"
f = open("user.txt","r",encding="utf-8")
f_new = open("new_user.txt","w",encoding="utf-8")
for line in f:
if old_str in line:
line = line.replace(old_str,new_str)
f_new.write(line)
f.close
f_new.close
此方法创建一个新的文件,从旧文件中逐行读取内容,再写到新文件里,若遇到需要修改的内容就用replace方法修改再写到新文件内