importsys,time

'''#文件句柄f = open("yesterday2",'a',encoding="utf-8")#'r'=read,'w'=write,w是建立文件.a=append追加的意思.默认读模式# print(f.read())#文件光标读取一遍f.write("我爱北京天安门.....\n")f.write("天安门上太阳升.....")#文件关闭f.close()'''# f = open("yesterday",'r',encoding="utf-8")# # print(f.readline())#只读一行# for i in range(5):# print(f.readline())#读前5行## f.close()# f = open("yesterday",'r',encoding="utf-8")# for line in f.readlines():# print(line.strip())#low loop# f = open("yesterday",'r',encoding="utf-8")# for index,line in enumerate(f.readlines()):# if index == 9:#取第10行数据# print('-----分割线-----')# continue# print(line.strip())#high bige# count = 0# f = open("yesterday",'r',encoding="utf-8")# for line in f:#一行一行读，效率最高## if count == 9:#取第10行数据# print('-----分割线-----')# count += 1# continue# print(line)# count += 1# f = open("yesterday",'r',encoding="utf-8")# print(f.tell())#打印文件句柄的光标位置,根据字符计数# print(f.readline())# print(f.read(5))# print(f.tell())# f.seek(0)#光标回到0位置# print(f.readline())# print(f.tell())# print(f.encoding)#打印文件编码# print(f.fileno())# print(f.isatty())#打印终端设备# print(f.flush())#刷新，实时刷新到硬盘上# f.truncate(10)#截断,从头开始截断。必须为a模式# f = open("yesterday2",'r+',encoding="utf-8")#可读写# # f1 = open("yesterday2",'w+',encoding="utf-8")#可写读# # f2 = open("yesterday2",'a+',encoding="utf-8")#追加读# # f3 = open("yesterday3",'rb')#二进制读，不能加encoding编码,网络传输必须用二进制打开# f4 = open("yesterday3",'wb')#二进制写，不能加encoding编码,网络传输必须用二进制打开# f4.write('hello world'.encode())#二进制写必须转换成str类型，不写就是默认utf-8模式## #写读是先建立一个文件，读写是读取在后面添加写入# print(f.readline())# print(f.readline())# print(f.readline())# f.write('-------diao--------\n')# print(f.read())# f.close()#flush 刷新输出# for i in range(50):# sys.stdout.write("*")# sys.stdout.flush()# time.sleep(0.1)#文件修改f = open("yesterday2",'r',encoding="utf-8")

f_new = open("yesterday4.bak",'w',encoding="utf-8")

forline inf :

if"我爱北京天安门"inline:

line = line.replace('我爱北京天安门','肆意的快乐等着cindy去享受')#old -- 将被替换的子字符串。new -- 新字符串，用于替换old子字符串。max -- 可选字符串, 替换不跨越 max 次print(line)

f_new.write(line)

f.close()

f_new.close()