std::nothrow

 

C++

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General utilities Date and time Function objects bitset Formatting library (C++20) hash (C++11) integer_sequence (C++14) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator> rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)    cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) forward (C++11) move (C++11) move_if_noexcept (C++11) as_const (C++17) to_underlying (C++23) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17) Stacktrace stacktrace_entry (C++23) basic_stacktrace (C++23)

 

Dynamic memory management

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Uninitialized memory algorithms uninitialized_copy uninitialized_fill uninitialized_move (C++17) uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) destroy (C++17) destroy_at (C++17) uninitialized_copy_n (C++11) uninitialized_fill_n uninitialized_move_n (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17) destroy_n (C++17) construct_at (C++20) Constrained uninitialized memory algorithms ranges::uninitialized_copy (C++20) ranges::uninitialized_fill (C++20) ranges::uninitialized_move (C++20) ranges::uninitialized_default_construct (C++20) ranges::uninitialized_value_construct (C++20) ranges::destroy (C++20) ranges::destroy_at (C++20) ranges::uninitialized_copy_n (C++20) ranges::uninitialized_fill_n (C++20) ranges::uninitialized_move_n (C++20) ranges::uninitialized_default_construct_n (C++20) ranges::uninitialized_value_construct_n (C++20) ranges::destroy_n (C++20) ranges::construct_at (C++20) Garbage collection support declare_reachable (C++11)(until C++23) undeclare_reachable (C++11)(until C++23) declare_no_pointers (C++11)(until C++23) undeclare_no_pointers (C++11)(until C++23) pointer_safety (C++11)(until C++23) get_pointer_safety (C++11)(until C++23) Miscellaneous pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) assume_aligned (C++20) C Library malloc aligned_alloc (C++17) calloc realloc free Low level memory management operator new operator new[] operator delete operator delete[] get_new_handler set_new_handler bad_alloc bad_array_new_length nothrow_t align_val_t destroying_delete_t new_handler nothrow

 

Low level memory management

Functions

operator newoperator new[]

operator deleteoperator delete[]

get_new_handler (C++11)

set_new_handler

Classes

bad_alloc

bad_array_new_length (C++11)

nothrow_t

align_val_t (C++17)

destroying_delete_t (C++20)

Types

new_handler

Objects

nothrow

 

Defined in header <new>
extern const std::nothrow_t nothrow;

std::nothrow is a constant of type std::nothrow_t used to disambiguate the overloads of throwing and non-throwing allocation functions.

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

See also

nothrow_t	tag type used to select an non-throwing allocation function (class)
operator newoperator new[]	allocation functions (function)