Explain file handling, file modes, file built in functions and built in methods

File Handling: File handling is an important part of any web application. Python has several functions for creating, reading, updating, and deleting files.

File Modes: File modes determine the type of operations allowed on the file. The most commonly used file modes are:

• 'r': Read mode which is used when the file is only being read.
• 'w': Write mode which is used to edit and write new information to the file.
• 'a': Appending mode, which is used to add new data to the end of the file.
• 'r+': Special read and write mode, which is used to handle both actions when working with a file.

File Built-in Functions: Python provides several built-in functions to work with files. Some of them are:

• open(): This function is used to open a file in the respective mode.
• close(): This function is used to close an already opened file.
• write(): This function is used to write data into the file.
• read(): This function is used to read data from the file.

Built-in Methods: Python provides several built-in methods to work with files. Some of them are:

• read(): This method reads the entire file.
• readline(): This method reads a file line by line.
• write(): This method writes a string to an open file.
• writelines(): This method writes a list of strings to the file.
• close(): This method closes the opened file. A closed file cannot be read or written any more.
• flush(): This method flushes the write buffer of the file stream.
• seek(offset[, from]): This method changes the current file position. The offset argument indicates the number of bytes to be moved. The from argument specifies the reference position from where the bytes are to be moved.
• tell(): This method returns the current file position.

File Handling: In Python, a file operation takes place in the following order.

• Open a file
• Read or write (perform operation)
• Close the file

File Modes: Python provides the following file modes for opening a file:

• 'r' - Read mode which is used when the file is only being read
• 'w' - Write mode which is used to edit and write new information to the file (any existing files with the same name will be erased when this mode is activated)
• 'a' - Appending mode, which is used to add new data to the end of the file; that is new information is automatically amended to the end
• 'r+' - Special read and write mode, which is used to handle both actions when working with a file

File Built-in Functions:

• open() function is used to open file. It returns a file object.
• close() function is used to close an opened file. It has no effect if the file is already closed.

File Built-in Methods:

• read() method is used to read a file’s contents. It takes an optional parameter that specifies the number of bytes to read.
• write() method is used to write data to files. It returns the number of characters written.
• seek() method is used to change the file position to the given reference position.
• tell() method returns the current file position.
• readline() method reads a line of a file.
• readlines() method reads all lines of a file.