File_handling.py

# Python File Open

# File handling is an important part of any web application.

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

# File Handling
# The key function for working with files in Python is the open() function.
# The open() function takes two parameters; filename, and mode.
# There are four different methods (modes) for opening a file:

# "r" - Read - Default value. Opens a file for reading, error if the file does not exist
# "a" - Append - Opens a file for appending, creates the file if it does not exist
# "w" - Write - Opens a file for writing, creates the file if it does not exist
# "x" - Create - Creates the specified file, returns an error if the file exists

# In addition you can specify if the file should be handled as binary or text mode

# "t" - Text - Default value. Text mode
# "b" - Binary - Binary mode (e.g. images)

# Syntax
# To open a file for reading it is enough to specify the name of the file:

f = open("demofile.txt")
# The code above is the same as:

f = open("demofile.txt", "rt")
# Because "r" for read, and "t" for text are the default values, you do not need to specify them.

# *Note: Make sure the file exists, or else you will get an error.

# Python has a set of methods available for the file object.

# Method	            Description
# close()	            Closes the file
# detach()	            Returns the separated raw stream from the buffer
# fileno()	            Returns a number that represents the stream, from the operating system's perspective
# flush()	            Flushes the internal buffer
# isatty()	            Returns whether the file stream is interactive or not
# read()	            Returns the file content
# readable()	        Returns whether the file stream can be read or not
# readline()	        Returns one line from the file
# readlines()	        Returns a list of lines from the file
# seek()	            Change the file position
# seekable()	        Returns whether the file allows us to change the file position
# tell()	            Returns the current file position
# truncate()	        Resizes the file to a specified size
# writable()	        Returns whether the file can be written to or not
# write()	            Writes the specified string to the file
# writelines()	        Writes a list of strings to the file