文件讀取

 1 # f=open('test.txt','r+')
 2 # f.write('Avaya')#新內容會添加在文件的開頭，並且會覆蓋開頭原有的內容
 3 # f.close()
 4 
 5 
 6 
 7 # f=open('test.txt','w')
 8 # f.write('test') #w模式下使用write，會把文件內容清空然後在開頭寫入內容
 9 # f.close()
10 
11 # f=open('test.txt','w+')
12 # f.write('test1')#效果與上面一樣
13 # f.close()
14 
15 # f=open('test.txt','a')
16 # f.write('Hillstone')  #會在文件末尾追加
17 # f.close()
18 
19 # f=open('test.txt')
20 # print(f.closed)#closed方法會返回一個布爾值，如果是打開狀態就是fales
21 # f.close()
22 # print(f.closed)
23 
24 
25 # with open('test.txt')as f:   #with語句打開的文件將自動關閉
26 #     print(f.read())
27 # print(f.closed)

異常

1 try:
2     print(5/0)
3 except ZeroDivisionError:
4     print("You can't divide by zero")
5 
6 You can't divide by zero

 1 filename='alice.txt'
 2 with open(filename) as f_obj:
 3     contents = f_obj.read()
 4 Python無法讀取不存在的文件，因此它引發一個異常：
 5 Traceback (most recent call last):
 6   File "E:/untitled1/alice.py", line 2, in <module>
 7     with open(filename) as f_obj:
 8 FileNotFoundError: [Errno 2] No such file or directory: 'alice.txt'
 9 
10 filename='alice.txt'
11 try:
12     with open(filename) as f_obj:
13         contents = f_obj.read()
14 except FileNotFoundError:
15     msg="Sorry,the file "+filename+" does not exist."
16     print(msg)

 1 filename='alice.txt'
 2 try:
 3     with open(filename) as f_obj:
 4         contents = f_obj.read()
 5 except FileNotFoundError:
 6     pass#不提示錯誤消息
 7 else:
 8     #  計算文件大致包含多少個單詞
 9     words= contents.split()
10     num_words=len(words)
11     print("The file "+filename+" has about "+str(num_words)+" words.")