Variadic Templates (C++11)

In a Nutshell

Allows templates to accept an arbitrary number of arguments of arbitrary types, providing a type-safe modern alternative to C-style variadic arguments (va_list).

Header

None required (language feature)

Core API Quick Reference

Operation	Signature	Description
Type parameter pack	typename... Ts	Accepts zero or more type arguments
Non-type parameter pack	Ts... args	Accepts zero or more non-type arguments
Template template parameter pack	template<typename> class... Ts	Accepts zero or more templates
Parameter pack expansion	args...	Expands a parameter pack into multiple expressions
Parameter pack size	sizeof...(args)	Returns the number of elements in the parameter pack
Fold expression	(args op ...) / (... op args)	C++17, applies a per-element operation over a parameter pack

Minimal Example

// Standard: C++11
#include <iostream>

template<typename... Ts>
void print(Ts... args) {
    // 利用初始化列表保证顺序地逐个打印
    int dummy[] = {(std::cout << args << " ", 0)...};
    (void)dummy;
}

int main() {
    print(1, "hello", 3.14);
}

Embedded Applicability: Medium

• Can completely replace unsafe va_list, improving type safety and code maintainability
• Template instantiation causes code bloat (increased binary size), so we need to monitor Flash usage
• Suitable for resource-rich scenarios (such as application processors running Linux); requires careful evaluation on bare-metal, low-end MCUs

Compiler Support

GCC	Clang	MSVC
4.3	2.9	TBD

See Also

• cppreference: Parameter packs

---

Some content adapted from cppreference.com under CC-BY-SA 4.0 license