Intentional Overflow [duplicate]

Question

I'm wondering if it is allowed in C++ to use overflow on purpose. In specific I want to increase a counter every cycle and when uint32_max is reached start from 0.

In my mind the easy way would be:

uint32_t counter = 0;
while(condition)
{
    counter++;
    ...
}

or would you manually reset the counter?:

uint32_t counter = 0;
while(condition)
{
    if(counter == uint32_max)
    {
        counter = 0;
    }
    else
    {
        counter++;
    }
    ...
}

Yes it's OK. Such "overflow" of unsigned integral values is well defined and behaves like you expect - i.e. wraps to 0 (this is not true for signed values though). — wohlstad
– wohlstad, Commented Nov 29, 2024 at 13:48
For standard unsigned integral types, it is fine to use overflow "on purpose", since the behaviour on overflow is well-defined by the C++ standard. For other types (e.g. signed integral types, floating point types) that is not true. — Peter
– Peter, Commented Nov 29, 2024 at 14:01
"on purpose" --What C++ allows and what it does not allow does not depend on the intent of the programmer. Better would be to ask if you can use overflow to reset a counter (i.e. if your desired behavior is guaranteed by the standard). — JaMiT
– JaMiT, Commented Nov 29, 2024 at 15:37

Lundin · Accepted Answer · 2024-11-29 13:48:34Z

4

That is fine because you used uint32_t. Unsigned integers do not overflow but wrap-around from the maximum value to zero. Such behavior is well-defined in C++, unlike signed integer overflow/underflow.

answered Nov 29, 2024 at 13:48

Lundin

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