Thread: Noob here, having trouble with simple program

Wait, you can assign to like an lvalue, right? Isn't (doube ) my_value an rvalue?

What? (double)SomeValue is a cast not an assignment. And no you can't cast a lvalue in a calculation.

Jim

Originally Posted by MutantJohn

Also, I didn't know that, is it really that easy to cast away constness using that? I always thought you had to do more nefarious things to effectively undermine const-ness

Const casting is actually one of the first things C++ tries to do to resolve (type)foo, it then tries static_cast, then a combination of static_cast and const cast to get to type. If all of those fail, then reinterpret_cast is used - the most permissive cast. The danger in C casting is the tendency to devolve into reinterpret_cast from some other mistake or from being short sighted about design.

Take this code, which only reinterpret_cast would compile.

Code:

int *v = something;
double d = double(v);

Forgetting the * is disastrous here.

C casting can be shorthand for something that you're sure will succeed before reinterpret_cast is used, so I don't necessarily blame you, but yeah it can remove const.