std::add_pointer
std::add_pointer
Defined in header <type_traits>
|
||
---|---|---|
|
(since C++11) |
If T
is a reference type, then provides the member typedef type
which is a pointer to the referred type.
Otherwise, if T names an object type, a function type that is not cv- or ref-qualified, or a (possibly cv-qualified) void type, provides the member typedef type
which is the type T*
.
Otherwise (if T is a cv- or ref-qualified function type), provides the member typedef type
which is the type T
.
Member types
Name | Definition |
---|---|
type
|
pointer to T or to the type referenced by T
|
Helper types
|
(since C++14) |
Possible implementation
|
Example
#include <iostream>
#include <type_traits>
int main()
{
int i = 123;
int& ri = i;
typedef std::add_pointer<decltype(i)>::type IntPtr;
typedef std::add_pointer<decltype(ri)>::type IntPtr2;
IntPtr pi = &i;
std::cout << "i = " << i << "\n";
std::cout << "*pi = " << *pi << "\n";
static_assert(std::is_pointer<IntPtr>::value, "IntPtr should be a pointer");
static_assert(std::is_same<IntPtr, int*>::value, "IntPtr should be a pointer to int");
static_assert(std::is_same<IntPtr2, IntPtr>::value, "IntPtr2 should be equal to IntPtr");
typedef std::remove_pointer<IntPtr>::type IntAgain;
IntAgain j = i;
std::cout << "j = " << j << "\n";
static_assert(!std::is_pointer<IntAgain>::value, "IntAgain should not be a pointer");
static_assert(std::is_same<IntAgain, int>::value, "IntAgain should be equal to int");
}
Output:
i = 123
*pi = 123
j = 123
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2101 | C++11 | std::add_pointer was required to producepointer to cv-/ref-qualified function types. |
Produces cv-/ref-qualified function types themselves. |
See also
(C++11) |
checks if a type is a pointer type (class template) |
(C++11) |
removes a pointer from the given type (class template) |
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