C++

20.3    Dangers of Aliasing

Did you notice that I secretly inserted the following into Listing 20.1?

values.reserve(50); // Ensure space for 50 values  

The reason for this is that I need to avoid a danger that arises from being able to access the same value—its memory range—in different ways. That is known as aliasing.

The vector also manages its data somewhere in memory. And one of its properties is that it promises to store them consecutively. However, this means that there might be no space left at the “back” of the vector when you add an element with push_back(). But vector handles this: it requests a new memory range twice as large and copies (or moves) all existing values to the new area. Finally, vector removes the old area.

Figure ...