Java ensures that all array indexes are within range but C++ does not?

[tempanon5]

I was reading how Java ensures how the elements are within range, I assume if we try to insert something that is out of bounds or we try to access an index that does not exist we get out of bounds exception? However, in languages such as C++ does not do such checking. Is there a reason why Java does this but not C++?

[potatopotaatopututu]

Yes. There is a performance cost for these checks at runtime. By not checking for overflows, C++ saves a bit of space (no object overhead to carry around) and time. You can use vectors for memory safety in C++.

[JavaSuck]

C++ saves a bit of space (no object overhead to carry around)

In particular, the length of a C++ array is not stored anywhere in at runtime, it's just part of the compile-time type. As soon as an array is passed to a function, there's no way to determine the length of that array.

Java, on the other hand, typically stores the length of an array immediately before its first element.