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When using std::nothrow, the new operator returns either a null pointer or a pointer to the allocated space. Always test the returned pointer to ensure it is not nullptr before referencing the pointer. This compliant solution handles the error condition appropriately when the returned pointer is nullptr:.
| Code Block | ||||
|---|---|---|---|---|
| ||||
#include <cstring>
#include <new>
void f(const int *array, std::size_t size) noexcept {
int *copy = new (std::nothrow) int[size];
if (!copy) {
// Handle error
return;
}
std::memcpy(copy, array, size * sizeof(*copy));
// ...
delete [] copy;
} |
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Alternatively, you can use ::operator new[] without std::nothrow and instead catch a std::bad_alloc exception if sufficient memory cannot be allocated:.
| Code Block | ||||
|---|---|---|---|---|
| ||||
#include <cstring>
#include <new>
void f(const int *array, std::size_t size) noexcept {
int *copy;
try {
copy = new int[size];
} catch(std::bad_alloc) {
// Handle error
return;
}
// At this point, copy has been initialized to allocated memory
std::memcpy(copy, array, size * sizeof(*copy));
// ...
delete [] copy;
} |
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When possible, the more resilient compliant solution is to remove the memory allocation entirely and pass the objects by reference instead:.
| Code Block | ||||
|---|---|---|---|---|
| ||||
struct A { /* ... */ };
struct B { /* ... */ };
void g(A &a, B &b);
void f() {
A a;
B b;
g(a, b);
} |
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