Python从新手到大师——10：文件操作

代码一

#! /usr/bin/env python
"""
@Time     : 2018/8/24 22:29
@Author   : Damao
@Site     : Life is short. I use python.
@File     : test1.py
@Software : PyCharm

"""
"""没有指定文件或文件不存在会报错"""

def test():
    f = open('abc.txt','r',encoding='utf-8')
    print(f.read())
    f.close()


if __name__ == '__main__':
    test()

代码二

#! /usr/bin/env python
'''
__Time__    : 2018/8/24 22:36
__Author__   : Damao
__Site__    : Life is short. I use python.
__File__     : test2.py
__Software__ : PyCharm
'''
"""处理异常"""

def main():
    f = None
    try:
        f = open('致橡树.txt', 'r', encoding='utf-8')
        print(f.read())
    except FileNotFoundError:
        print('无法打开指定的文件!')
    except LookupError:
        print('指定了未知的编码!')
    except UnicodeDecodeError:
        print('读取文件时解码错误!')
    finally:
        if f:
            f.close()


if __name__ == '__main__':
    main()

代码三

#! /usr/bin/env python
'''
__Time__    : 2018/8/24 22:41
__Author__   : Damao
__Site__    : Life is short. I use python.
__File__     : test3.py
__Software__ : PyCharm
'''

"""with语句"""

def main():
    try:
        with open('致橡树.txt','r',encoding='utf-8') as f:
            print(f.read())
    except FileNotFoundError:
        print('无法打开指定的文件!')
    except LookupError:
        print('指定了未知的编码!')
    except UnicodeDecodeError:
        print('读取文件时解码错误!')


if __name__ == '__main__':
    main()

代码四

#! /usr/bin/env python
'''
__Time__    : 2018/8/24 22:44
__Author__   : Damao
__Site__    : Life is short. I use python.
__File__     : test4.py
__Software__ : PyCharm
'''

"""多种方式读取文件"""
def test():
    # 一次性读取所有文件内容
    with open('致橡树.txt','r',encoding='utf-8') as f:
        print(f.read())

    # for循环读取
    with open('致橡树.txt',mode='r',encoding='utf-8') as f:
        for i in f:
            print(i,end='')

    # 按行读取文件到列表中
    with open('致橡树.txt', mode='r', encoding='utf-8') as f:
        l = []
        for i in f:
            l.append(i[:-2])
            # if i[-2:] == '\n':
            #     # i = i[:-2]
            #     l.append(i[:-2])
        for index in range(len(l)-1):
            if l[index] == '':
                del l[index]
        print(l)
        # lines = f.readlines()
        # print(lines)


if __name__ == '__main__':
    test()

代码五

#! /usr/bin/env python
'''
__Time__    : 2018/8/24 22:57
__Author__   : Damao
__Site__    : Life is short. I use python.
__File__     : test5.py
__Software__ : PyCharm
'''
a = '1213213213'
print(a[:-2])
print(a[-2:])

代码六

#! /usr/bin/env python
'''
__Time__    : 2018/8/24 23:12
__Author__   : Damao
__Site__    : Life is short. I use python.
__File__     : test6.py
__Software__ : PyCharm
'''
from math import sqrt


def is_prime(n):
    """判断素数的函数"""
    assert n > 0
    for factor in range(2, int(sqrt(n)) + 1):
        if n % factor == 0:
            return False
    return True if n != 1 else False


def main():
    filenames = ('C:\\MYTEST\\a.txt', 'C:\\MYTEST\\b.txt', 'C:\\MYTEST\\c.txt')
    fs_list = []
    try:
        for filename in filenames:
            fs_list.append(open(file=filename, mode='w', encoding='utf-8'))
        for number in range(1, 10000):
            if is_prime(number):
                if number < 100:
                    fs_list[0].write(str(number) + '\n')
                elif number < 1000:
                    fs_list[1].write(str(number) + '\n')
                else:
                    fs_list[2].write(str(number) + '\n')
    except IOError as ex:
        print(ex)
        print('写文件时发生错误!')
    finally:
        for fs in fs_list:
            fs.close()
    print('操作完成!')


if __name__ == '__main__':
    main()

代码七

#! /usr/bin/env python
'''
__Time__    : 2018/8/25 21:34
__Author__   : Damao
__Site__    : Life is short. I use python.
__File__     : test7.py
__Software__ : PyCharm
'''

"""读写二进制文件，下面代码实现复制文件的功能"""

def test():
    try:
        with open(file='mm.jpg',mode='rb') as f:
            data = f.read()
        with open(file='C:\\MYTEST\\copy_mm.jpg',mode='wb') as f1:
            f1.write(data)
    except FileNotFoundError as e:
        print("文件未找到",e)
    except IOError as e:
        print("读写文件时错误",e)
    print("程序执行完毕。")


if __name__ == '__main__':
    test()

代码八

#! /usr/bin/env python
'''
__Time__    : 2018/8/25 21:50
__Author__   : Damao
__Site__    : Life is short. I use python.
__File__     : test8.py
__Software__ : PyCharm
'''
"""
保存json格式文件

    dump - 将Python对象按照JSON格式序列化到文件中
    dumps - 将Python对象处理成JSON格式的字符串
    load - 将文件中的JSON数据反序列化成对象
    loads - 将字符串的内容反序列化成Python对象

"""

import json


def test_save_json_data():
    json_data ={
                'name': 'damao',
                'age': 1,
                'qq': 123456,
                'friends': ['小红', '小明'],
                'cars': [
                    {'brand': 'BYD', 'max_speed': 180},
                    {'brand': 'Audi', 'max_speed': 280},
                    {'brand': 'Benz', 'max_speed': 320}
                     ]
                }
    try:
        with open(file='C:\\MYTEST\\test_json_data.json',mode='w',encoding='utf-8') as f:
            json.dump(json_data,f)
    except IOError as e:
        print("读写错误",e)
    print("json数据保存成功！")

def test_read_json_filedata():
    try:
        with open(file="C:\\MYTEST\\test_json_data.json",mode='r',encoding='utf-8') as f:
            a = json.load(f)
            print(json.dumps(a,ensure_ascii=False,indent=4,separators=(':',',')))  # 格式化json数据输出
    except IOError as e:
        print("读写错误", e)
    print("json数据读取成功！")


if __name__ == '__main__':
    # test_save_json_data()
    test_read_json_filedata()