In addition to the differences you cite, and the library differences that Steve Jessop mentions, char* p1; char const* const* p2 = &p1; is legal in C++, but not in C. Historically, this is because C originally allowed: char* p1; char const** p2 = &p1; Shortly before the standard was adopted, someone realized that this … Read more
int Random() const { return var_ ? const_cast<ClassType*>(this)->newCall(4) : 0; } But it’s not a good idea. Avoid if it’s possible!
My take on it: It’s not a bad idea, but the issue is minor and your energy might be better spent on other things. In your question you provided a good example of when it might catch an error, but occasionally you also end up doing something like this: void foo(const int count /* … … Read more
See Why am I getting an error converting a Foo** → const Foo**? Because converting Foo** → const Foo** would be invalid and dangerous … The reason the conversion from Foo** → const Foo** is dangerous is that it would let you silently and accidentally modify a const Foo object without a cast The reference … Read more
In C, there’s no such thing as a function being const or otherwise, so a pointer to a const function is meaningless (shouldn’t compile, though I haven’t checked with any particular compiler). Note that although it’s different, you can have a const pointer to a function, a pointer to function returning const, etc. Essentially everything … Read more
const is pointless when the argument is passed by value since you will not be modifying the caller’s object. Wrong. It’s about self-documenting your code and your assumptions. If your code has many people working on it and your functions are non-trivial then you should mark const any and everything that you can. When writing … Read more
The objects in the std::set are stored as const StudentT. So when you try to call getId() with the const object the compiler detects a problem, mainly you’re calling a non-const member function on const object which is not allowed because non-const member functions make NO PROMISE not to modify the object; so the compiler … Read more
When you apply the const qualifier to a nonstatic member function, it affects the this pointer. For a const-qualified member function of class C, the this pointer is of type C const*, whereas for a member function that is not const-qualified, the this pointer is of type C*. A static member function does not have … Read more
const is pointless when the argument is passed by value since you will not be modifying the caller’s object. Wrong. It’s about self-documenting your code and your assumptions. If your code has many people working on it and your functions are non-trivial then you should mark const any and everything that you can. When writing … Read more
However, in main, I pass the same variable, referenced both by a and by b. As f modifies b, it also modifies a, which it supposedly shouldn’t When f modifies what b refers to, it does not modify a. It modifies what a refers to, but that is okay since b is not const. It’s … Read more