1、文件读写简单实例:(以w写的方式打开一个文件,以r读一个文件)
# Author : xiajinqi# 文件读写的几种方式
# 文件读写
f = open("D://test.txt","w",encoding="utf-8")
f.write("hello world")
f.flush()
f.close()f = open("D://test.txt","r",encoding="utf-8")
data = f.read()
data2 = f.read()
f.seek(0,0)
data3 = f.read()
print("data-------------------",data)
print("data2------------------",data2)
print("data3-----------------",data3)
2、文件写的w和a 简单介绍
# Author : xiajinqi# 文件读写的几种方式
# 文件写,文件写,如果就文件存在,会清空旧文件内容(切记),如果不存在就创建。并且不能读
f = open("test.txt","w",encoding="utf-8")
f.write("hello world1\n")
f.write("hello world2\n")
f.write("hello world3\n")
f.flush()
f.close()f = open("D://test.txt","r",encoding="utf-8")
data = f.read()
print(data)
f.close()# 文件追加,不能读,在文件尾部追加,不会清空旧的文件
f = open("test.txt","a",encoding="utf-8")
f.write("追加1")
f.close()f = open("test.txt","a",encoding="utf-8")
f.write("\n追加2")
f.close()f = open("test.txt","r",encoding="utf-8")
data = f.read()
print(data)
f.close()执行结果
E:\Users\xiajinqi\PycharmProjects\twoday\venv\Scripts\python.exe E:/Users/xiajinqi/PycharmProjects/twoday/file.py
hello world1
hello world2
hello world3hello world1
hello world2
hello world3
追加1
追加2Process finished with exit code 0
3、文件读r的详细使用。文件读的几种方式和优缺点:
# Author : xiajinqi
# 文件读按照行数读
#方式一,读全部内容(文件太大时候,内存会爆掉)
f = open("test.txt","r",encoding="utf-8")
print("一次性读出来--------------")
print(f.read())
f.close() #方式2,一行一行读readline ,读出所有的行,并且转换为数组f.readlines()
#由于一直在往内存读,导致内存会爆掉,这种循环又称为low
f = open("test.txt","r",encoding="utf-8")
print("一行一行读low looper--------------")
for key,line in enumerate(f.readlines()):
print(key,line.strip())
f.close() # 方式3 :文件循环读。内存每次只有一行,读一行,关闭一行,内存永远不会爆掉。建议使用3,效率最高
f = open("test.txt","r",encoding="utf-8")
print("一行一行读bigger looper--------------")
for line in f :
print(line.strip())
f.close()
4、练习题目 ,实现第九行不打印的两种方式
方式一:
f = open("test.txt","r",encoding="utf-8")
print("不打印第九行")
count = 0
for line in f :
count = count + 1
if count == 9 :
print("分隔符>>>>>>>>>>>>>>>>>>>")
continue
print(line.strip())
f.close()方式二:
f = open("test.txt","r",encoding="utf-8")
print("不打印第九行方式二")
for key,line in enumerate(f.readlines()) :
if key == 8 :
print("分隔符>>>>>>>>>>>>>>>>>>>")
continue
print(key+1,line.strip())
f.close()
5、seek(),tell() 介绍和总结:
#tell 记录当前指针的位置(字符位置),seek设置指针的位置f = open("test.txt","r",encoding="utf-8")
print("第一次打印")
print(f.read())
print(f.read()) # 指针已经到了文件尾部,继续读将为空
print("第二次打印")
f.seek(0,0)
print(f.read())
f.close()#查找当前位置
f = open("test.txt","r",encoding="utf-8")
f.readline()
print(f.tell())
f.close()
6、文件的其他函数总结:
#
f = open("test.txt","r",encoding="utf-8")
print("其他函数使用")
print(f.fileno()) #文件在系统中的编号,一般
print(f.name) #文件名字
print(f.seekable()) #终端设备无法移动
print(f.readable()) #文件是否可以读
f.close()
7、flush 使用。将内存数据写到文件(系统默认不是实时刷新)
import sys,time
# 显示进度条
for i in range(10) :
sys.stdout.write("#")
sys.stdout.flush()
time.sleep(0.2)