Python File Input/Output

File Input/Output in Python

Reading Files

• open() function: used to open a file and return a file object
  • Syntax: file_object = open(file_name, mode)
  • Modes:
    • r: read mode (default)
    • w: write mode
    • a: append mode
    • r+, w+, a+: read and write mode
• read() method: reads the entire file and returns a string
  • Syntax: file_content = file_object.read()
• readline() method: reads a single line from the file and returns a string
  • Syntax: line = file_object.readline()
• readlines() method: reads all lines from the file and returns a list of strings
  • Syntax: lines = file_object.readlines()

Writing Files

• write() method: writes a string to the file
  • Syntax: file_object.write(string)
• writelines() method: writes a list of strings to the file
  • Syntax: file_object.writelines(list_of_strings)

Closing Files

• close() method: closes the file
  • Syntax: file_object.close()
• with statement: automatically closes the file when done
  • Syntax: with open(file_name, mode) as file_object: ...

Other File I/O Functions

• print() function: can be used to write to a file
  • Syntax: print(string, file=file_object)
• input() function: can be used to read from a file
  • Syntax: input_string = input(prompt, file=file_object)

File Modes

• Binary Mode: used to read and write binary data
  • Syntax: open(file_name, 'rb') or open(file_name, 'wb')
• Text Mode: used to read and write text data (default)
  • Syntax: open(file_name, 'r') or open(file_name, 'w')

File Input/Output in Python

Reading Files

• The open() function is used to open a file and return a file object, with a syntax of file_object = open(file_name, mode).
• The mode parameter specifies the mode of opening the file, with options including r for read mode (default), w for write mode, a for append mode, and r+, w+, a+ for read and write mode.
• The read() method reads the entire file and returns a string, with a syntax of file_content = file_object.read().
• The readline() method reads a single line from the file and returns a string, with a syntax of line = file_object.readline().
• The readlines() method reads all lines from the file and returns a list of strings, with a syntax of lines = file_object.readlines().

Writing Files

• The write() method writes a string to the file, with a syntax of file_object.write(string).
• The writelines() method writes a list of strings to the file, with a syntax of file_object.writelines(list_of_strings).

Closing Files

• The close() method closes the file, with a syntax of file_object.close().
• The with statement automatically closes the file when done, with a syntax of with open(file_name, mode) as file_object:....

Other File I/O Functions

• The print() function can be used to write to a file, with a syntax of print(string, file=file_object).
• The input() function can be used to read from a file, with a syntax of input_string = input(prompt, file=file_object).

File Modes

• Binary mode is used to read and write binary data, with a syntax of open(file_name, 'rb') or open(file_name, 'wb').
• Text mode is used to read and write text data (default), with a syntax of open(file_name, 'r') or open(file_name, 'w').

Learn about reading and writing files in Python, including the open() function and read() and readline() methods.