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BasicOpenFile.md

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File Handling

Basic Of File

  • A file is some information or data which stays in the computer storage devices.

  • Generally, we divide files into two categories, text file, and binary file. Text files are the simple text whereas the binary files contain binary data which is only readable by a computer

  • Python has several functions for creating, reading, updating, and deleting files.

There are mainly different 3 operations can be performed on the file.

 - Open file
 - Read or write file
 - close file.

1.Opening File

  • for opening a file in Python one named open() methods are available.

  • The open function takes two arguments

    • filename
    • mode of file

Syntax:

File_to_open=open(filename,mode)

Where Filename; required Mode:is optional bydefault mode is read

Following are some modes which are helpful while dealing with file

1. r 

  • Read mode
  • This mode opens a file for reading purposes.
  • If the file does not exist this will generate an error.

Syntax:

fileobj=open(filename,"r")

Example:

fileobj=open("myfile.txt","r")

Above example give an error if file is not exists.

2. a 

  • Append mode
  • This mode is used when we want to append content to the end of the file without overwintering the previous content.
  • If the file does not exist a mode creates a new file.

Syntax:

fileobj=open(filename,"a")

Example:

fileobj=open("myfile.txt","a")

3. w

  • Write mode
  • This mode is used when we want to overwrite some content to file.
  • If the file does not exist it will create a new file.

Syntax:

fileobj=open(filename,"w")

Example:

fileobj=open("myfile.txt","w")

4. x 

  • Exclusive Create.
  • This mode is used to create a specified file.
  • If the file already exists then it will give an error

Syntax:

fileobj=open(filename,"x")

Example:

fileobj=open("myfile.txt","x")

the file should be handled as binary or text mode using the following 2 modes

  1. b binary file
  2. t text file

Example 1:

Consider mylog.txt file in your current directory and you want to open it

#defualt read mode
fil=open("mylog.txt")

#Using r mode
fil=open("mylog.txt","r")

#using read and text mode
fil=open("mylog.txt","rt")

Above all example open a text file for reading the purpose

Example 2:

Open file for writing purpose

fil=open("mylog.txt","w")

How to add multiple modes to file object

When you want to read and write on the same file you can pass both modes to open() function

Syntax:

fileobj=open(filename,"mode1mode2")

Example:

fileobj=open("myfile.txt","rwt")

Here file is opened in three different mode for reading,writing a text file

Note:after completion of file operation don't forgot to close file using filename.close()

Open a file with "with" statement

  • With the with statement, you get better syntax and exceptions handling.
  • Using with keyword the file is automatically closed when the operation is completed.we don't need to write
fileobj.close()

Syntax:

with open(filename,mode) as fileobj:
         #do operation on fileobj

Example:

Consider mytext.txt contains

Hello I am from file

with open("mytext.txt","r") as file:
    content=file.read()
    print(content)

Output:

Hello I am from file