文件

相关函数

• close：关闭文件
• read：读取文件的内容，可以把结果赋值给一个变量
• readline：只读取文本文件中的一行
• truncate：清空文件【谨慎使用】
• write('stuff')：将'stuff'写入文件
• seek(0):将读写位置移动到文件开头

读取文件

• 使用open()获取文件对象 2.使用read()读取内容
• eg

from sys import argv 
scrpit,fliename = argv 
txt = open(fliename) 
print(f"Here's your file {fliename}") print(txt.read())
txt.close()

读写文件

• eg

from sys import argv 
scrpit, filename = argv 
print(f"We're going to erase{filename}.") 
print("If you don't want that,hit CTRL_C(^C)") print(" If you do want that,hit RETURN")
input("?")
print("Opening the file...")
target = open(filename,'w') 
print("Truncating the file.Goodbye!") target.truncate() 
print("I'm going to ask you for this lines.") 
line1 = input("line 1") 
line2 = input("line 2")
line3 = input("line 3") 
print("I'm going to write these to the file.") target.write(line1) 
target.write("\n")
target.write(line2) 
target.write("\n") target.write(line3) target.write("\n")
print("And finally,we close it.") 
target.close()

open()

• 传入的值
  • 传入 'w': “写入（write）模式”
  • 传入'r' : ”读取（read）“
  • 传入'a' : "追加(append)"
  • open(filename) ，不加传入的值表示用只读模式打开

复制文件内容

• 判断文件是否存在
  • 使用exitsts
  • 导入方法：from os.path import exists
• eg

from sys import argv 
from os.path import exists

script,from_file,to_file = argv 

print (f"Coping from {from_file} to {to_file}")
in_file = open(from_file)
indatas = in_file.read() 

print(f"The input file is {len(indatas)} bytes long")

print(f"Does the output file exitst? {exists(to_file)}") 
print("Ready,hit RETURN to continue,CTRL-C to abort") 
input() 

out_file = open(to_file,'w')
out_file.write(indatas) 

print("Alright,all done") 

out_file.close() in_file.close()