File Handling
It’s important and powerful feature of Python and it is widely used in Web application Where we can create, edit, delete and update the file in run time.
The main functions used in File Handling are open
There are basically four different modes for opening file:
| “r” (read) | This mode is used for reading the file. |
| “a” (append) | This mode is used for inserting data into existing files. |
| “w”(write) | This mode is used for writing something on file. |
| “x”(exclusive) | This mode is used for create new file but raised failed if file already exists |
| “+”(advance) | It gives advance feature to exist mode |
| “t” (text) | Default value is Text mode |
| “b”(binary) | Binary mode |
Syntax
f=open(“example.txt”,”mode”)
Program for Create file
f=open("demo.txt","w")
f.write("Hello How Are You ?")#write something
print("File Successfully Create")
f.close()#closing file
Output
File Successfully Create
Program for ReadFile
f=open("demo.txt","r")
print(f.read())
f.close()
Output
Hello How Are You ?
Program for Append or Update(if we used ‘w’ mode then old file demo.txt will replace with new one)
f=open("demo.txt","a")
f.write(" Using append mode ")
print("file append successfully")
f.close()
Output
file append successfully
Program for Read Append File
f=open("demo.txt","r")
print(f.read())
f.close()
Output
Hello How Are You ? Now I am using Append Mode
Program for Exclusive
f=open("demo.txt","x")
f.write("x mode")
If we create an existing file.
Output
Traceback (most recent call last): File "C:/Users/laptop/Desktop/hello.py", line 1, inf=open("demo.txt","x") FileExistsError: [Errno 17] File exists: 'demo.txt'
Program with rectify
f=open("demo1.txt","x")
f.write("x mode")
print("successfully create")
Output
successfully create
Let’s start with Advance mode(+)
+ used postfix with exist mode to enhance facility of another
| r+ | Read+Write |
| w+ | Write+Read |
| a+ | Append+Read |
| x+ | Create+Read |
Here we are describe two function are used with Advance mode
| seek(argument) | This function is used to adjust the cursor position. |
| tell() | This is used for know the current position of the cursor. |
Program with Advance Mode
f=open("demo.txt","w+")
f.write("I am creating file and write something")
print("Current Position",f.tell())
print("After used seek",f.seek(0))
print(f.read())
f.close()
Output
Current Position 38 After used seek 0 I am creating file and write something