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I think C++ is really powerful, read the following

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Hello...

I think C++ is really powerful, read the following:

I have said before that C++ allows some "implicit" conversions
and that is not good, but i have learned more C++ and now i
am understanding it more, and i think C++ is really powerful !
because you can "control" implicit conversiosn(that means disallowing 
implicit conversions) by doing the following in C++, look carefully at 
the following C++ code that you can extend:


===

include <iostream>
#include <stdexcept>

struct controlled_int {
   // allow creation from int
   controlled_int(int x) : value_(x) { };
   controlled_int& operator=(int x) { value_ = x; return *this; };
   // disallow assignment from bool; you might want to use 
BOOST_STATIC_ASSERT instead
   controlled_int& operator=(bool b) { std::cout << "Exception: Invalid 
assignment of bool to controlled_int" << std::endl;
throw; return *this; };

   // creation from bool shouldn't happen silently
   explicit controlled_int(bool b) : value_(b) { };

   // conversion to int is allowed
   operator int() { return value_; };

   // conversion to bool errors out; you might want to use 
BOOST_STATIC_ASSERT instead

   operator bool() { std::cout << "Invalid conversion of controlled_int 
to bool" << std::endl;
// throw std::logic_error("Exception: Invalid conversion of 
controlled_int //to bool");
};

   private:
     int value_;
};

int main()
{
   controlled_int a(42);

   // This errors out:
   // bool b = a;
   // This gives an error as well:
   a = true;

   std::cout << "Size of controlled_int: " << sizeof(a) << std::endl;
   std::cout << "Size of int: " << sizeof(int) << std::endl;

   return 0;
}


===

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I think C++ is really powerful, read the following Sky89 <Sky89@sky68.com> - 2018-06-05 20:01 -0400

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