Defined in header <new> | ||
|---|---|---|
struct nothrow_t {};
| (until C++11) | |
struct nothrow_t { explicit nothrow_t() = default; };
| (since C++11) | |
extern const std::nothrow_t nothrow; |
std::nothrow_t is an empty class type used to disambiguate the overloads of throwing and non-throwing allocation functions. std::nothrow is a constant of it.
#include <iostream>
#include <new>
int main()
{
try
{
while (true)
{
new int[100000000ul]; // throwing overload
}
}
catch (const std::bad_alloc& e)
{
std::cout << e.what() << '\n';
}
while (true)
{
int* p = new(std::nothrow) int[100000000ul]; // non-throwing overload
if (p == nullptr)
{
std::cout << "Allocation returned nullptr\n";
break;
}
}
}Output:
std::bad_alloc Allocation returned nullptr
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2510 | C++11 | the default constructor was non-explicit, which could lead to ambiguity | made explicit |
| allocation functions (function) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/memory/new/nothrow