---
title: "Variadic templates in C++"
description: "Variadic templates in C++11: parameter packs, recursive expansion with a base case, C++17 fold expressions, and where they are used."
date: 2023-04-06
last_modified_at: 2026-10-02
keywords: [C++, variadic templates, parameter pack, fold expressions, C++17]
---

# Variadic Templates in C++

Variadic templates, introduced in C++11, allow you to define templates that accept an arbitrary number of arguments of any type.

## Basic Syntax

```cpp
template<typename... Args>
return_type function_name(Args... args);
```

The ellipsis (`...`) indicates a parameter pack, which can contain zero or more template arguments.

## Recursive Implementation Example

A common pattern is to use recursion to process variadic templates:

```cpp
// Base case to terminate recursion
void print() {
    std::cout << std::endl;
}

// Recursive case
template<typename T, typename... Args>
void print(T first, Args... rest) {
    std::cout << first << " ";
    print(rest...); // Recursive call with remaining arguments
}

// Usage
print(1, 2.5, "hello", 'c'); // Outputs: 1 2.5 hello c
```

## Fold Expressions (C++17)

C++17 introduced fold expressions to simplify variadic template code:

```cpp
template<typename... Args>
auto sum(Args... args) {
    return (... + args); // Unary left fold
}

// Usage
int total = sum(1, 2, 3, 4, 5); // 15
```

## Applications

Variadic templates are particularly useful for:
- Creating type-safe variadic functions
- Implementing perfect forwarding
- Building tuple-like data structures
- Creating compile-time type lists