pointer to constant
#include <iostream>
int main() {
int variable = 42;
const int* ptr = &variable;
std::cout << "Value of variable: " << variable << std::endl;
std::cout << "Value pointed to by ptr: " << *ptr << std::endl;
// Compilation error: Cannot modify a const-qualified variable
// *ptr = 20;
variable = 20;
std::cout << "Updated value of variable: " << variable << std::endl;
std::cout << "Updated value pointed to by ptr: " << *ptr << std::endl;
return 0;
}