What does it mean "regular file" according to S_ISREG C/C++?

Question

Let's consider the following 3 code lines:

struct stat buffer;       
status = lstat(file.c_str(), &buffer);  
bool Flag = S_ISREG(buffer.st_mode)

When S_ISREG() returns true it tells you that the file is a regular file

What does regular means exactly ?

Thanks

Answer 1

It is non-standard, you should check the documentation for your CRT implementation. But it ought to mean that the name refers to a regular file, instead of a pipe, stream, symbolic link, directory or device.

Answer 2

Regular means it's not a directory, not a symlink, not a block device, and not a character device. It's just... regular. :)