Variadic Templates (C++11)

One-Liner

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

Header

None required (language feature)

Core API Cheat Sheet

Operation	Syntax	Description
Type parameter pack	typename... Ts	Accepts zero or more type arguments
Non-type parameter pack	int... Is	Accepts zero or more non-type arguments
Template template parameter pack	template<typename> class... Templates	Accepts zero or more templates
Parameter pack expansion	Ts...	Expands the parameter pack into multiple expressions
Parameter pack size	sizeof...(Ts)	Returns the number of elements in the parameter pack
Fold expression (unary)	(expr op ...)	C++17, performs per-element operation on the pack
Fold expression (binary)	(init op ... op expr)	C++17, performs per-element operation on the pack

Minimal Example

// 打印所有参数的函数
// Function to print all arguments
template <typename... Ts>
void print_all(Ts... args) {
    ((std::cout << args << " "), ...); // C++17 折叠表达式 (Fold expression)
}

int main() {
    print_all(1, "Hello", 3.14); // 输出: 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 monitor Flash usage.
• Suitable for resource-rich scenarios (e.g., application processors with Linux); careful evaluation is needed on bare-metal low-end MCUs.

Compiler Support

GCC	Clang	MSVC
4.3	2.9	TBD

See Also

• cppreference: Parameter packs

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