笨方法学Python——习题16

# -*- coding:utf-8 -*-
from sys import argv

script, filename = argv

print "We're going to erase %r." % filename
print "If you don't want that, hit CTRL-C(^c)."
print "If you do want that, hit RETURN."

raw_input("?")

print "Opening the file..."
target = open(filename, "w")
# 这里的 w 应该是重点，还有 r a 等多种用法，脑细胞不够用了
print "Truncating the file. Goodbye!"
target.truncate()
# 这里暂时没懂，网上说这个应该具有截断的功能，但删除这行代码，运行时又没有什么影响
print "Now I'm going to ask you for three lines."

line1 = raw_input("line 1: ")
line2 = raw_input("line 2: ")
line3 = raw_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()
# 这里习题用了多个函数，raw_input()、open()、truncate()、write()、close()
# 先用 open 指令打开文档，