How to convert a float pointer to an int pointer in C++?

Question

I understand that reinterpret_cast may do it, but I think it did not do the data conversion. I don't want to loop over and do them one by one, and wonder whether there is an elegant way to do both the pointer type and data type conversion. Thanks!

We need more scope to this. That alone sounds like a bad idea. — Qaz
– Qaz, Commented Nov 29, 2012 at 20:05
Hi, could explain what you mean by "We need more scope to this"? — Hailiang Zhang
– Hailiang Zhang, Commented Nov 29, 2012 at 20:09
Create a SSCC(C)E -- sscce.org -- that describes what you want to do. It should compile, even if there is a step you don't understand. Describe what the more general problem is that you want to solve -- provide some context to the short self contained example as well. — Yakk - Adam Nevraumont
– Yakk - Adam Nevraumont, Commented Nov 29, 2012 at 20:11

Joseph Mansfield · Accepted Answer · 2012-11-29 20:16:25Z

3

If, as I am assuming, you have some float* that points to the first element in an array of floats and you want to use them as ints then I suggest a few options:

If you don't want float, don't get floats. Just store an array of ints in the first place.
Likewise, if you don't want ints, then change your code to use floats throughout.
If you do indeed want to have an array of floats and at some point want to convert them to ints, do it when you need it. Use static_cast<int> to do the conversion on each element in a safe manner.
If you'd like to convert the whole array at once, then I suggest you do something like so:
```
float float_array[N] = /* ... */;
std::vector<int> ints(float_array, float_array + N);
```
Alternatively, if you really want to stick with arrays, use std::copy:
```
float float_array[N] = /* ... */;
int int_array[N];
std::copy(float_array, float_array + N, int_array);
```
The std::vector above is much preferred, however.

answered Nov 29, 2012 at 20:16

Joseph Mansfield

111k22 gold badges249 silver badges329 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Hailiang Zhang Over a year ago

Great answers! Apparently I don't want to use 3. My scenario is convert a float array to an int array, and load this int array to GPU. I am not sure the GPU API will take STL object or not, so I may need to do 5. However, if the STL vector can be easily converted or casted to a regular array, maybe I can do it. Thanks!

Collectives™ on Stack Overflow

How to convert a float pointer to an int pointer in C++?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related