C++: Template Metaprogramming

Uses the classic enum hack.

template<unsigned int n>
struct factorial {
    enum { result = n * factorial<n - 1>::result };
};

template<>
struct factorial<0> {
    enum { result = 1 };
};

Usage.

unsigned int x = factorial<4>::result;

Factorial is calculated completely at compile time based on the template parameter n. Therefore, factorial<4>::result is a constant once the compiler has done its work.

C++: Template Metaprogramming

Uses the classic enum hack.

template<unsigned int n>
struct factorial {
    enum { result = n * factorial<n - 1>::result };
};

template<>
struct factorial<0> {
    enum { result = 1 };
};

Usage.

const unsigned int x = factorial<4>::result;

Factorial is calculated completely at compile time based on the template parameter n. Therefore, factorial<4>::result is a constant once the compiler has done its work.

C++: Template Metaprogramming

uses the classic enum hack

template<unsigned n>
struct factorial {
    enum { result = n * factorial<n - 1>::result };
};

template<>
struct factorial<0> {
    enum { result = 1 };
};

usage

int x = factorial<4>::result;

C++: Template Metaprogramming

Uses the classic enum hack.

template<unsigned int n>
struct factorial {
    enum { result = n * factorial<n - 1>::result };
};

template<>
struct factorial<0> {
    enum { result = 1 };
};

Usage.

unsigned int x = factorial<4>::result;

Factorial is calculated completely at compile time based on the template parameter n. Therefore, factorial<4>::result is a constant once the compiler has done its work.