What exactly is or was the purpose of C++ function-style casts?

by

Function style casts bring consistency to primitive and user defined types. This is very useful when defining templates. For example, take this very silly example:

template<typename T, typename U>
T silly_cast(U const &u) {
  return T(u);
}

My silly_cast function will work for primitive types, because it’s a function-style cast. It will also work for user defined types, so long as class T has a single argument constructor that takes a U or U const &.

template<typename T, typename U>
T silly_cast(U const &u) {
    return T(u);
}

class Foo {};
class Bar {
public:
    Bar(Foo const&) {};
};

int main() {
    long lg = 1L;
    Foo f;
    int v = silly_cast<int>(lg);
    Bar b = silly_cast<Bar>(f);
}

More Related Contents:

  1. Can I use the result of a comparison as an integer in C++?
  2. Regular cast vs. static_cast vs. dynamic_cast [duplicate]
  3. Multi-character constant warnings
  4. Is it safe to delete a void pointer?
  5. C++ cast syntax styles
  6. What does casting to `void` really do? [duplicate]
  7. Can I assume (bool)true == (int)1 for any C++ compiler?
  8. Why does C++ need a separate header file?
  9. Converting a pointer into an integer
  10. C++ convert from 1 char to string?
  11. Function pointers casting in C++
  12. Cast pointer to member function to normal pointer
  13. C++: rationale behind hiding rule
  14. Reinterpret_cast vs. C-style cast
  15. C++ auto vs auto&
  16. Can I cast a derived class to a private base class, using C-style cast?
  17. Passing shared_ptr as shared_ptr
  18. Is reinterpret_cast type punning actually undefined behavior?
  19. Why doesn’t this reinterpret_cast compile?
  20. Is it OK to use C-style cast for built-in types?
  21. std::lexical_cast – is there such a thing?
  22. Understanding gsl::narrow implementation
  23. Purpose of a “.f” appended to a number?
  24. Why aren’t there compiler-generated swap() methods in C++0x?
  25. Why isn’t operator overloading for pointers allowed to work?
  26. Should I use a C++ reinterpret_cast over a C-style cast?
  27. What’s the motivation behind having copy and direct initialization behave differently?
  28. Why Doesn’t reinterpret_cast Force copy_n for Casts between Same-Sized Types?
  29. How to cast simple pointer to a multidimensional-array of fixed size?
  30. How can I extend a lexical cast to support enumerated types?

Leave a Comment