std::nothrow(3) | C++ Standard Libary | std::nothrow(3) |
NAME¶
std::nothrow - std::nothrow
Synopsis¶
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.
Example¶
// Run this code
#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
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 2510 C++11 the default constructor was non-explicit, which made explicit
could lead to ambiguity
See also¶
operator new allocation functions
operator new[] (function)
2022.07.31 | http://cppreference.com |