file operation in binary vs text mode — performance concern

Question

In many projects, I saw that data object/structure are written into file in binary mode, and then retrieve them back from the file in binary mode again.

I wonder why

Answer 1

If you read/write a file in a text mode, you are operating text. It might be a subject of encoding errors, and OS-specific format changes, though sometimes it may work just fine. In binary mode, though, you will not meet these restrictions. Also, text mode may do funny things with \n characters, such as replacing them with \n\r.

Fopen reference, for example, says:

In the case of text files, depending on the environment where the application runs, some special character conversion may occur in input/output operations to adapt them to a system-specific text file format. In many environments, such as most UNIX-based systems, it makes no difference to open a file as a text file or a binary file; Both are treated exactly the same way, but differentiation is recommended for a better portability.