Question

Please consider the following code:

float float_value = x; // x is any valid float value
int int_value = 0;
size_t size = sizeof(int) < sizeof(float) ? sizeof(int) : sizeof(float);
memcpy(&int_value, &float_value, size);

As far as i know this could result in an trap representation. My questions:

1. Is that true?
2. If not, why?
3. If not, is there another way avoiding a possible trap representation?

Answer 1

The sanctioned way which won’t produce any trap representation is

unsigned char obj[sizeof float];
memcpy(obj, &float_value, sizeof float);

Then you can use the bytes of the object representation to build your desired int.

But using fixed-width integers as mentioned by Stephen Canon is better – unless you have a weird float size.