---
title: "Template metaprogramming in C++: compile-time factorial"
description: "Compute factorials at compile time in C++ with a recursive class template and a Factorial<0> base case, so the result has no runtime cost."
date: 2023-04-06
last_modified_at: 2026-10-02
keywords: [C++, template metaprogramming, compile-time computation, factorial, templates]
---

# Template Metaprogramming - Factorial

Another classic example of template metaprogramming is computing factorials at compile time.

## Factorial Implementation

```cpp
template<int N>
struct Factorial {
    static const int value = N * Factorial<N-1>::value;
};

// Base case
template<>
struct Factorial<0> {
    static const int value = 1;
};
```

This implementation allows factorial computations to be performed during compilation. The template is recursively instantiated until it reaches the base case of `Factorial<0>`, which returns 1.

To use this implementation, simply access the `value` member of the appropriate template instantiation:

```cpp
int main() {
    std::cout << "Factorial of 5: " << Factorial<5>::value << std::endl; // 120
    return 0;
}
```

The computation happens at compile time, resulting in no runtime overhead for the calculation.