Head First Python第3、4章学习笔记

sketch.txt
Man: Is this the right room for an argument?
Other Man: I've told you once.
Man: No you haven't!
Other Man: Yes I have.
Man: When?
Other Man: Just now.
Man: No you didn't!
Other Man: Yes I did!
Man: You didn't!
Other Man: I'm telling you, I did!
Man: You did not!
Other Man: Oh I'm sorry, is this a five minute argument, or the full half hour?
Man: Ah! (taking out his wallet and paying) Just the five minutes.
Other Man: Just the five minutes. Thank you.
Other Man: Anyway, I did.
Man: You most certainly did not!
Other Man: Now let's get one thing quite clear: I most definitely told you! #一行多个:
Man: Oh no you didn't!
Other Man: Oh yes I did!
Man: Oh no you didn't!
Other Man: Oh yes I did!
Man: Oh look, this isn't an argument!
(pause) #没有:
Other Man: Yes it is!
Man: No it isn't!
(pause)
Man: It's just contradiction!
Other Man: No it isn't!
Man: It IS!
Other Man: It is NOT!
Man: You just contradicted me!
Other Man: No I didn't!
Man: You DID!
Other Man: No no no!
Man: You did just then!
Other Man: Nonsense!
Man: (exasperated) Oh, this is futile!!
(pause)
Other Man: No it isn't!
Man: Yes it is!


***=opne()
***.close()
os.chdir()切换目录
os.getcwd()查看当前目录
readline()获取一行数据
seek()回到文件起始位置
split("*")以某个符号为分隔符,默认尽可能多的分割
split("",1)分割一次
无法更改的常量列表叫元组
数据不符合期望格式ValueError
数据无法正常访问IOError
方法一:考虑每种异常
import os
if os.path.exists('sketch.txt'):    
    data = open('sketch.txt')
    for each_line in data:
        if not each_line.find(':') == -1:
            (role, line_spoken) = each_line.split(':',1)
            print(role),
            print('said:'),
            print(line_spoken),
    data.close()
else:
    print("The file is missing!")
方法二:增加异常处理
try:
    data = open('sketch.txt')
    for each_line in data:
        try:
            (role, line_spoken) = each_line.split(':')
            print(role),
            print('said:'),
            print(line_spoken),
        except:
            pass
    data.close()
except:
    print("The file is missing!")
推荐使用异常处理,但是需要指定异常而不是所有异常统一处理

为代码增加输出
print("",file=*)
open("*.out","w")#追加a,写和读w+
读写都需要close()

输出到屏幕
man = []
other = []
try:
    data = open('sketch.txt')
    for each_line in data:
        try:
            (role, line_spoken) = each_line.split(':',1)
            line_spoken = line_spoken.strip() #删除空白
            if role == 'Man':
                man.append(line_spoken)
            elif role == 'Other Man':
                other.append(line_spoken)
        except ValueError:
            pass
    data.close()
except IOError:
    print("The file is missing!")
print(man)
print(other)

输出到文件
man = []
other = []

try:
    data = open('sketch.txt',encoding='utf8')
    for each_line in data:
        try:
            (role, line_spoken) = each_line.split(':',1)
            line_spoken = line_spoken.strip()
            if role == 'Man':
                man.append(line_spoken)
            elif role == 'Other Man':
                other.append(line_spoken)
        except ValueError:
            pass
    data.close()  
except IOError:
    print("The file is missing!")
    
try:
    man_file=open('man_data.txt','w')
    other_file=open('other_data.txt','w')
    print(man,file=man_file)
    print(other,file=other_file)
    #man_file.close()modify:把close移到finally,保证关闭
    #other_file.close()   
except IOError:
    print('File error.')
finally:
    if 'man_file' in locals(): #增加文件不存在的判断
        man_file.close()
    if 'other_file' in locals():
        other_file.close()

优化close&&日志版
man = []
other = []

try:
    with open('sketch.txt',encoding='utf8') as data: #使用with替代finally
        for each_line in data:
            try:
                (role, line_spoken) = each_line.split(':',1)
                line_spoken = line_spoken.strip()
                if role == 'Man':
                    man.append(line_spoken)
                elif role == 'Other Man':
                    other.append(line_spoken)
            except ValueError:
                pass  
except IOError as Ierr:
    print("error:"+str(Ierr))
    
try:
    with open('man_data.txt','w') as man_file:
        print(man,file=man_file)
    with open('other_data.txt','w') as other_file:
        print(other,file=other_file)  
except IOError as err: #输出具体错误
    print('File error:'+str(err)) #BIF要求异常对象为字符串

修改print_lol函数使输出的文件满足一定格式

将输出的文件持久储存

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