C++ Const Cast

const_cast<new_type>(expression)

const int* ptr = nullptr;
int* modifiable_ptr = const_cast<int*>(ptr);       // Valid: Base type is 'int'
// char* char_ptr = const_cast<char*>(ptr);        // Error: Cannot change base type

const int val = 10;
// int new_val = const_cast<int>(val);             // Error: new_type must be a pointer or reference
const int& ref = val;
int& modifiable_ref = const_cast<int&>(ref);       // Valid: Operates on a reference

int x = 5;
int* p = &x;
const int* cp = const_cast<const int*>(p);         // Valid: Adding constness

int original_non_const = 42;
const int* ptr_to_const = &original_non_const;

// Cast away constness
int* modifiable_ptr = const_cast<int*>(ptr_to_const);

// Valid: The original object in memory is not const.
*modifiable_ptr = 100; 

const int original_const = 42;
const int* ptr_to_const = &original_const;

// Cast away constness (The cast itself is legal)
int* modifiable_ptr = const_cast<int*>(ptr_to_const);

// UNDEFINED BEHAVIOR: Attempting to write to memory declared as const.
// The compiler may have placed 'original_const' in read-only memory (ROM).
*modifiable_ptr = 100;