has_trivial_constructor Class
Tests if type has trivial default constructor.
template<class Ty>
struct has_trivial_constructor;
Parameters
- Ty
The type to query.
Remarks
An instance of the type predicate holds true if the type Ty is a class that has a trivial constructor, otherwise it holds false.
A constructor for a class Ty is trivial if:
it is an implicitly declared default constructor
the class Ty has no virtual functions
the class Ty has no virtual bases
all the direct bases of the class Ty have trivial constructors
the classes of all the non-static data members of class type have trivial constructors
the classes of all the non-static data members of type array of class have trivial constructors
Example
// std_tr1__type_traits__has_trivial_constructor.cpp
// compile with: /EHsc
#include <type_traits>
#include <iostream>
struct trivial
{
int val;
};
struct throws
{
throws() throw(int)
{
}
throws(const throws&) throw(int)
{
}
throws& operator=(const throws&) throw(int)
{
}
int val;
};
int main()
{
std::cout << "has_trivial_constructor<trivial> == " << std::boolalpha
<< std::has_trivial_constructor<trivial>::value << std::endl;
std::cout << "has_trivial_constructor<throws> == " << std::boolalpha
<< std::has_trivial_constructor<throws>::value << std::endl;
return (0);
}
has_trivial_constructor<trivial> == true has_trivial_constructor<throws> == false
Requirements
Header: <type_traits>
Namespace: std