Are they operators '+' and '-' to manipulate the signness of their operands?
I now know I meant unary plus and minus operators!
I've never seen this operator before.
Have they been introduced in C++11 or later C++ standards?
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You mean add and subtract? – meowgoesthedog Jun 28 '17 at 08:35
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I don't mean add and subtract. – Jumogehn Jun 28 '17 at 08:35
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3Unary + and - ? They exist since forever – StoryTeller - Unslander Monica Jun 28 '17 at 08:35
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1Better call them unary minus and unary plus operators – Basile Starynkevitch Jun 28 '17 at 08:35
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1You mean you can write a positive number like `+123` or a negative like `-123`? That's pretty basic and has been with C++ since the beginning. How else would one even be able to use negative numbers or values in general without an unary negation operator? – Some programmer dude Jun 28 '17 at 08:36
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2http://en.cppreference.com/w/cpp/language/operator_arithmetic – Edgar Rokjān Jun 28 '17 at 08:36
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Yes, I meant unary plus and minus!! – Jumogehn Jun 28 '17 at 08:43
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Easily googlable with "C++ operators" or similar terms. Second hit for me is to [cppreference](http://en.cppreference.com/w/cpp/language/operator_precedence), listing `+a` and `-a` in the table. – Angew is no longer proud of SO Jun 28 '17 at 09:09
2 Answers
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Unary + and - have existed since the early formulations of C in the 1970s.
Note that + is not a no-op: it will widen the argument to at least an int type.
Finally note that -1 is not a literal in C++: it is a compile-time evaluable constant expression consisting of the unary negation of the int literal 1.
Bathsheba
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Regarding the "not no-op", one also have to remember that in C++ these operators can also be overloaded. – Some programmer dude Jun 28 '17 at 08:40
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1It will also decay arrays, functions and capture-less lambdas into pointers :) – Quentin Jun 28 '17 at 08:41
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^ - Which is all useful to ensure specific template argument deduction or overload resolution – StoryTeller - Unslander Monica Jun 28 '17 at 08:42
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Yes, C++ has signed operators.
int a;
a = -20; //valid
a = a + (-30) //valid
Read about signed and unsigned data types here and unary operators here.
Saurabh Shrivastava
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