# @Time     :2019/6/8 20:57

'''

练习题1 —— 全局替换程序：

1.写一个脚本，允许用户按以下方式执行时，即可以对指定文件内容进行全局替换

    python your_script.py old_str new_str filename

2.替换完毕后打印替换了多少处内容

'''

import os

import sys

my_sys = sys.argv  # 接收输入的参数

if len(my_sys) != 4:

    print("Wrong inputing!")

    os._exit(0)

else:

    print("Replacing....")

old_str = str(my_sys[1])

new_str = str(my_sys[2])

filename = my_sys[3]

new_file = filename + "_new"

count = 0

with open(filename, mode='r', encoding='utf-8') as f:

    data = f.read()

    if old_str in data:

        data = data.split("\n")  # 用\n分割字符串输出为列表

        f_new = open(new_file, mode='w', encoding='utf-8')  # 创建了文本迭代器

        for i in data:

            if old_str in i:

                count += 1

            i = i.replace(old_str, new_str)

            f_new.write(i + "\n")  # 写入文件

        f_new.close()

if count > 0:

    if os.path.exists(filename):

        os.remove(filename)

    os.replace(new_file, filename)

    print("替换成功,替换了{0}处".format(count))

else:

    print("{0}文件中没有{1}".format(filename, old_str))