vector

Acceleration from device’s coordinate system into absolute coordinate system

I finally managed to solve it! So to get acceleration vector in Earth’s coordinate system you need to: get rotation matrix (float[16] so it could be used later by android.opengl.Matrix class) from SensorManager.getRotationMatrix() (using SENSOR.TYPE_GRAVITY and SENSOR.TYPE_MAGNETIC_FIELD sensors values as parameters), use android.opengl.Matrix.invertM() on the rotation matrix to invert it (not transpose!), use Sensor.TYPE_LINEAR_ACCELERATION sensor … Read more

How to filter a vector of custom structs?

It’s very important programming skill to learn how to create a minimal, reproducible example. Your problem can be reduced to this: struct Vocabulary; fn main() { let numbers = vec![Vocabulary]; let other_numbers: Vec<Vocabulary> = numbers.iter().collect(); } Let’s look at the error message for your case: error[E0277]: a collection of type `std::vec::Vec<Vocabulary>` cannot be built from … Read more

C++ – value of uninitialized vector

The zero initialization is specified in the standard as default zero initialization/value initialization for builtin types, primarily to support just this type of case in template use. Note that this behavior is different from a local variable such as int x; which leaves the value uninitialized (as in the C language that behavior is inherited … Read more

C++ trying to swap values in a vector

I think what you are looking for is iter_swap which you can find also in <algorithm>. all you need to do is just pass two iterators each pointing at one of the elements you want to exchange. since you have the position of the two elements, you can do something like this: // assuming your … Read more

Write concurrently vector

Concurrent writes to vector<bool> are never ok, because the underlying implementation relies on a proxy object of type vector<bool>::reference which acts as if it was a reference to bool, but in reality will fetch and update the bitfield bytes as needed. When using multiple threads without synchronization, the following might happen: Thread 1 is supposed … Read more

What happen to pointers when vectors need more memory and realocate memory?

Short answer: Everything will be fine. Don’t worry about this and get back to work. Medium answer: Adding elements to or removing them from a vector invalidates all iterators and references/pointers (possibly with the exception of removing from the back). Simple as that. Don’t refer to any old iterators and obtain new ones after such … Read more