You can open .DAT files that contain text, with text editors, like Notepad, Notepad++, VS Code, etc. But it is not possible to know what contains in a DAT file.

Importing Notepad in C++. By default, the Windows Notepad saves files as a collection of plain ASCII text with a .txt file extension, but Notepad can also create header files, source files or text ...

And Notepad defaults to margin settings that don’t accommodate a typical 80-column text file. If you want a quick hard copy of your plain text files, the formatting change may distract from ...