Avoid std :: bad_alloc. new should return a null pointer

Question

I am migrating a mid-size application from C to C ++. It has nothing to do with exceptions, and this should not change.

Understanding (C ++) my (wrong!) Understanding was (until I found out about it hard) that the new operator (by default) returns a NULL pointer in case of a distribution problem. However, this was only true until 1993 (or so). It is currently throwing an std :: bad_alloc exception.

Is it possible to return to the old behavior without rewriting everything to use std :: nothrow with every call?

Answer 1

You can overload the new operator:

#include <vector>

void *operator new(size_t pAmount) // throw (std::bad_alloc)
{
    // just forward to the default no-throwing version.
    return ::operator new(pAmount, std::nothrow);
}

int main(void)
{
    typedef std::vector<int> container;

    container v;
    v.reserve(v.max_size()); // should fail
}

Answer 2

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#include <new>

int main() {
    int* p = new(std::nothrow) int;
    if (p) {
        delete p;
    }
}

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Answer 3

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Answer 4

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Answer 5

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