python 文件修改的两个方式

# with open('test.txt','r+',encoding='utf-8') as f:
#     f.seek(3) #偏移量单位是字节
#     # print(f.tell())#  看光标的位置,
#     f.write('[小马哥]')

# 修改文件方式一.
# 1.先把文件内容全部读入内存
# 2.然后再内存中完成修改
# 3.再把修改后的结果覆盖写入文件
# 缺点:会在文件内容过大的情况下占用过多的内存,机器有可能卡死

# with open('test.txt','r',encoding='utf-8') as f:
#     data = f.read()
#     data=data.replace('赵','小马哥[最帅]')
# with open('test.txt','w',encoding='utf-8') as f:
#     f.write(data)


# 修改文件方式二.
# 1.以读的方式打开原文件,以写的方式打开一个新文件
# 优点:不在过分的耗费内存,但消耗硬盘,但最终还是删除原文件
# import os
# with open('test.txt','r',encoding='utf-8') as read_f,\
#     open('a2.txt','w',encoding='utf-8') as write_f:
#     for line in read_f:
#         if '钱' in line:
#             line=line.replace('钱','tom[第二帅]')
#         #     write_f.write(line)
#         # else:
#         write_f.write(line)
# os.remove('test.txt')
# os.rename('a2.txt','test.txt')