File Handling

File Handling

Introduction

  • File handling is the process of creating, reading, writing, and closing files using programming.
  • In programming, a file is a container in a computer system where data is stored.

Opening Files

  • Before a file can be read or written to, it must be opened using a file handling command in the programming language you’re using.
  • This command will return a file handle, which is like a cursor that you can control to read or write data at different positions in the file.
  • Files can be opened in different modes, including ‘read’ (r), ‘write’ (w), ‘append’ (a), and others.

Reading Data

  • Reading data from a file is called file input.
  • This involves opening the file in ‘read’ mode, then using a function or command to read data from the file.
  • Reading can happen in many ways - for example, you might read the entire file at once, or you might read the file a line at a time.

Writing Data

  • Writing data to a file is called file output.
  • This involves opening the file in ‘write’ or ‘append’ mode, and then using a function or command to write data to the file.
  • Be aware that opening a file in ‘write’ mode will erase any existing data in the file.
  • ‘Append’ mode will allow you to add data to the end of the file without erasing existing data.

Closing Files

  • Once you are finished with a file, it’s important to close it.
  • Closing a file makes sure that any changes you made are saved and that system resources are freed up.
  • Not closing a file can result in data loss or data corruption.

File Paths

  • Files are located on your computer’s file system by their File Path.
  • This path starts at a root directory and specifies every folder and subfolder until it reaches the file.
  • File paths can be absolute, meaning they start from the root of the file system, or relative, meaning they start from the current directory.

Error Handling

  • File handling often involves error handling, as many things can go wrong, such as a file not existing, a file not opening correctly, a read or write operation failing, and more.
  • Errors can be handled with try…except blocks in Python and similar constructs in other languages.
  • Handling errors gracefully can make your program more robust and user-friendly.