cc6 - Casts - EVAL

[nuoxoxo]

ex00 - $\color {Orange} \text {EVAL} $

• Use and only use static_cast to convert values
• check w/ $ grep _cast -R .
• - implicit type casting -
  • - definition -
• it means the destination data type is not specified, and is therefore automatically done by the compiler / at "compile time"
• why use static cast? because sometimes more than one data type is present in an expression
  • - eg. -
• 0 is a bool, a non-printable char and an int
• int can be unsigned, long, long long, float, double...
• so the compiler allows type promotion to happen to avoid loss of data
• - implicit cast is unsafe -
  • - risks -
• signs can be lost converting signed to unsigned
• overflow can occur converting long long to float
• - How to do this -
  • - logic -
• Up-casting means promotion
• Promotion implies hierarchy
• we apply Harl (or Karen) levels
  • Types "char - int - float - double" are checked in order
  • Once confirmed, creates an Scalar object, prints and returns
• - Uncompromising? -
  • "Yes."

    ex01 - $\color {Orange} \text {EVAL} $

• _- reinterpret_cast<> Used Twice -_
  • of course
  • once Serializing to unsigned int uint_t
  • the other time Deserializing it back to Data *

    
    static  Data *deserialize(uintptr_t _) {
    return (reinterpret_cast<Data*>(_));
    }

static uintptrt serialize(Data * ) { return (reinterpret_cast(_)); }

- ___- Is the struct Useful ?? -___ 
  - of course
    - see _main_
# ex02 - $\color {Orange} \text {EVAL} $ 
- `void identify (Base *p)` should check if _dynamic_cast<>_ returns 0/NULL
  - ❗ on failure 
   - <kbd> dynamic_cast<_new_type_>(*) </kbd> return a NULL point of _new_type_ 
- `void identify (Base & p)` should check with `try...catch`
  - ❓ why `try...catch`
  - BECAUSE you can have a null pointer, but not a null reference - any reference has to be bound to an object.
  - SO when <kbd>dynamic_cast</kbd> for a pointer type fails it returns a null pointer which we can check
  - BUT when it fails for a reference type, it cannott return a ___null reference___, so an 
- ___-  "header must not appear anywhere" -___ 
  - No idea what it means.