Meta programming: Variadic templates

21 Dec, 2017  in C++11  tagged c+11 by Robert

---

Syntax

C++

template <typename T, typename... Args> void printf(const char *format, T value, Args... args);

1 2	template <typename T, typename... Args> void printf(const char *format, T value,  Args... args);

 

C++

template <typename T> long long getSumOfPows(T t) { return t*t; } template <typename T, typename... Rest> long long getSumOfPows(T t, Rest... rest) { return getSumOfPows(t) + getSumOfPows(rest...); } long mySum = getSumOfPows(1,2,3,4,5,6,7);

1 2 3 4 5 6 7

template <typename T> long long getSumOfPows(T t) {     return t*t; }   template <typename T, typename... Rest> long long getSumOfPows(T t, Rest... rest) {     return getSumOfPows(t) + getSumOfPows(rest...); }   long mySum = getSumOfPows(1,2,3,4,5,6,7);

• Variadic templates essentially allow recursion to be replaced by iteration
• Variadic templates needs an end function – usually it’s a specialization for the last remaining parameter, in order to stop the recursion. This has changed in C++17 and is no longer needed.

---