Contenido del Curso
C++ Templates
C++ Templates
Compile-Time Computation with Templates
Templates are not just a tool for creating generic algorithms and data structures; they also unlock the power of compile-time computation. This technique allows for the execution of certain programs during the compilation phase, leading to optimized and faster executable code.
Understanding Factorial Calculation
Factorial, denoted as "n!", is the product of a positive integer and all the positive integers below it. For instance, 4! = 4 * 3 * 2 * 1 = 24. Traditionally, the factorial function is implemented recursively, with a runtime computation for any given input n. This approach, while straightforward, doesn't leverage the knowledge of n at compile time, leading to unnecessary runtime calculations.
Traditional Implementation
main
#include <iostream> int factorial(int n) { if (n == 0) return 1; else return n * factorial(n - 1); } int main() { std::cout << factorial(4); // Computes 24 at runtime }
This method computes factorial(4) at runtime, which is not efficient when the value of n is known at compile time.
Compile-Time Computation with Templates
To harness the full potential of compile-time computation, we use template metaprogramming. This approach computes the factorial at compile time, thus eliminating runtime overhead and shrinking the code footprint.
main
#include <iostream> template <int N> struct Factorial { static const int value = N * Factorial<N - 1>::value; }; template <> struct Factorial<0> { // Base case specialization static const int value = 1; }; int main() { std::cout << Factorial<4>::value; // 24, computed at compile time }
In this template-based meta-program, Factorial
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