Python基础学习四 文件操作（二）

####读取文件####

with open('goods_info.txt', 'r', encoding='utf-8') as f:

f.seek(0) # 注意指针位置

goods_info = eval(f.read()) # eval()将字符串str当成有效的表达式来求值并返回计算结果

####内容替换####

with open('123.txt','a+',encoding='utf-8') as f:

f.seek(0)

all = f.read()

new_all = all.replace('二','一')

f.seek(0)

f.truncate()

f.write(new_all)

f.flush()

####多文件读取####

import os

with open('123.txt',encoding='utf-8') as f,open('333.txt','w',encoding='utf-8') as f2:

for line in f:

new_line = line.replace('一','二')

f2.write(new_line)

os.remove('123.txt')#删文件

os.rename('123.txt','333')#改名

###图片读写#####

在博客上，上传一张图片，保存图片的URL

import requests

url = 'https://images2017.cnblogs.com/blog/1297828/201801/1297828-20180111115848004-1702177202.jpg'

img = requests.get(url).content

f = open('123.jpg','wb')# bytes ，以二进制模式打开

f.write(img)