c++ - What is decltype and how is it used? - Stack Overflow
otherwise, decltype(e) is the type of e. Note that the first bullet covers decltype(a), and the subsequent bullets cover double parentheses cases like decltype((b)). Combining these rules with reference collapsing rules allows you to make sense of decltype(e) &&, which is always a "suitable" reference.
c++ - What are some uses of decltype (auto)? - Stack Overflow
2014年6月9日 · The example that always prompts this disgust is the one-liner file-to-string syntax (also mentioned in that link).
c++ - When should I use decltype (x) instead of auto to declare …
2014年1月27日 · I see decltype(x) used inside macros where x is a variable name because the type of the object isn't known inside macros. For example: decltype(x) y = expr; I could just have easily use auto instead of decltype. So what are those situations where decltype is needed for a variable type declaration instead of auto?
What is the difference between decltype and auto as a …
decltype is a broader construct that, at the cost of extra information, will infer the type of an expression.
c++ - What is decltype with two arguments? - Stack Overflow
The decltype with two arguments first looked surprising to me, as I thought it just gets the type of an expression. When I saw the code above, I thought it's something like "try to compile the expressions and always return the type of the second.
c++ - What is the difference between auto and decltype(auto) …
decltype is useful when you mainly want to operate with types (not variables), e.g. in traits that check if some expression has a certain type. – Kerrek SB Commented Jan 26, 2014 at 21:18
c++ - decltype, result_of, or typeof? - Stack Overflow
2015年1月24日 · decltype is a standard C++11 feature. It is an "operator" which takes an expression and returns a type. typedef typename decltype( T().toCPD() ) D; // can't use T:: as it's nonstatic If T() isn't a valid (T not default-constructible) you will want declval which is a function that takes a type and returns a meaningless, invalid value of that type.
c++ - Difference between decltype and typeof? - Stack Overflow
2013年1月2日 · int a = 1; int& ra = a; typeof(a) b = 1; // int typeof(ra) b2 = 1; // int decltype(a) b3; // int decltype(ra) b4 = a; // reference to int The name typeof was the preferred choice (consistent with sizeof and alignof , and the name already used in extensions), but as you can see in the proposal N1478 , concern around compatibility with existing ...
Enlightening Usage of C++11 decltype - Stack Overflow
2014年6月8日 · decltype(x) is not necessarily the same as decltype((x))). For example, it's likely your Standard library ...
Why is decltype defining a variable as a reference?
decltype and auto are very useful additions to C++, a sound understanding of their meaning and use is very useful especially if they are being used in the code. In client type code, auto will probably be much more common. What is decltype()? decltype offers a mechanism to get to the type given a variable or expression. It generally features in ...