Computer Science – File handling | e-Consult

Several file access modes are available to programs, each with a specific purpose:

• Read (r): Allows the program to read data from the file. The file must exist.
  Example: Opening a text file to display its contents to the user.
• Write (w): Allows the program to write data to the file. If the file exists, its contents are overwritten. If the file doesn't exist, a new file is created.
  Example: Creating a new log file and writing application messages to it.
• Append (a): Allows the program to write data to the end of the file. If the file doesn't exist, a new file is created.
  Example: Adding new entries to a log file without overwriting existing data.
• Read and Write (r+): Allows the program to both read from and write to the file. The file must exist.
  Example: Opening a file to read some data, modify it, and then save the changes back to the same file.
• Append and Read (a+): Allows the program to both append data to the end of the file and read from it. If the file doesn't exist, a new file is created.
  Example: Adding new data to a log file and then immediately reading the entire file to display the latest entries.

Choosing the correct mode is crucial to avoid accidentally overwriting data or encountering errors.