Question

I ran into an interesting line of code today. I did not know it was legal to use the word “or”. I thought there was only ||.
What is this called and where can I read more about it?
Thanks

if (V_discount == "y" or "Y" or "Yes" or "yes")
           {
               cout << "Your discount is: ";
}

edit: It turns out the if statement doesn’t do much. I put a cout<<“hi”; in the brackets, and it executes regardless of what V_discount has in it.

I thought it was called something because netbeans is highlighting “or” in blue.

2nd edit:

v == "y" || "Y" 

is not the same as

v == "y" || v == "Y"

Only the latter functions “as intended”. “As intended” being checking whether v is the string “y” or v is the string “Y”.

Answer 1

It’s called an “alternative token”, documented in section 2.6 [lex.digraph] of the current ISO C++ standard, and in section 2.5 of the 1998 ISO C++ standard. (This is the same section that defines “digraphs”, such as <% for { and %: for #.)

But the code you’ve shown uses it incorrectly.

First, if x were an int, then you’d probably want this:

if (x == 10 or x == 20 or x == 30)

rather than this:

if (x == 10 or 20 or 30)

The latter is actually legal, but it means something quite different.

And comparing strings for equality is not straightforward. If V_discount is a char* or char[], then comparing V_discount == "yes" compares pointer values, not the contents of the strings, and they’ll certainly compare unequal. If V_discount is a std::string, then I think it will work — but you still have to compare it to each of the literals individually. Otherwise, as Tony Delroy’s answer says, it compiles but does something entirely unexpected involving implicit conversions to bool.