C++ constexpr vs const

1. constexpr vs const

constexpr

• known at compile time

const

• means “promise not to change”
• who promises not to change what?

2. const

const variable

• const int pi

const reference

• const Foo &foo

const pointer

• char *const p

pointer to const

• const char *p

const methods

• promise that the method will not change the member variable
• void method() const

C++ casting

static_cast

always defined behavior and known at compile time

dynamic_cast

always defined behavior but might fail at runtime. Used typically for inheritance relationship.

const_cast

only used to remove const. (your API design sucks! so go back and review your code)

reinterpret_cast

Forcing compiler to do what you want to do when you do something weird

(int)

don’t do this.