python入门_文件的写入

 

import random
from datetime import datetime


def write_file():
    """ 写入文件 """
    file_name = "write_test.txt"
    f = open(file_name, 'w')
    f.write('hellow')
    f.write('\n')
    #换行符\n、\r、\r\n
    f.write('world')

    #关闭文件
    f.close()

def write_mult_line():
    """ 向文件中写入多行内容 """
    file_name = 'write_mult_line.txt'
    with open(file_name, 'w',encoding='utf-8') as f:
        l = ['第一行','\n','第二行','\n\r','第三行',]
        f.writelines(l)

def write_user_log():
    """ 记录用户的日志 """
    #记录时间 + 记录用户的ID
    rest = 'ID{0},时间{1}'.format(random.randint(1000,9999), datetime.now())
    # print(rest)
    file_name = 'write_user_log.txt'
    with open(file_name, 'a', encoding='utf-8') as f:
        f.write(rest)
        f.write('\n')

def read_and_write():
    """ 先读，后写 """
    file_name = 'read_and_write.txt'
    with open(file_name, 'r+', encoding='utf-8') as f:
        read_rest = f.read()
        #如果内容没有1，就写一行aaa
        #如果内容有1，就写一行bbb
        if '1' in read_rest:
            f.write('\n')
            f.write('bbb')
        else:
            f.write('\n')
            f.write('aaa')

if __name__ == '__main__':
    # write_file()
    #write_mult_line()
    #write_user_log()
    read_and_write()