#ifndef CLASS_NAME_Hused as more or less the standard and not
#pragma onceand how does the preprocessor handle both cases?
#pragma oncenot mentioned in the article is that with it, the include guard is not predictable. This may be of importance if your program has a large number of header files (say 500) with deeply nested nested #include directives.
Pragma directive [cpp.pragma]
1 A preprocessing directive of the form # pragma pp-tokensopt new-line
causes the implementation to behave in an implementation-defined manner. The behavior might cause
translation to fail or cause the translator or the resulting program to behave in a non-conforming manner.
Any pragma that is not recognized by the implementation is ignored.
#pragma oncebecause I actually learned this way when I was doing my work placement with a huge multinational company.