What are the Advantages and Applications of Non-Type Template Parameters in C ?

Non-Type Template Parameters in C

Introduction

In C , templates allow the creation of generic functions and classes that can operate on different data types. Traditionally, templates are declared with type parameters, such as template. However, C also supports non-type template parameters, which can be used to specify compile-time constants or other non-type parameters.

What Are Non-Type Template Parameters?

Non-type template parameters are template parameters that are not types. They can be:

• Pointers
• References
• Integral constant expressions

Benefits of Non-Type Template Parameters

Non-type template parameters offer several benefits:

• They allow for compile-time customization of templates based on constant values.
• They can be used to define default values for template parameters.
• They can reduce code duplication and improve maintainability.

Syntax for Non-Type Template Parameters

Non-type template parameters are declared using the template<> syntax, followed by the type of the parameter and its name:

<code class="cpp">template<unsigned int N>
class Vector {
    // ...
};</code>

In this example, N is a non-type template parameter of type unsigned int.

Examples of Non-Type Template Parameters

• Compile-Time Constant: The following template takes a compile-time constant S as a parameter to specify the size of a vector:

<code class="cpp">template<unsigned int S>
struct Vector {
    unsigned char bytes[S];
};

Vector<3> test; // Creates a vector with 3 elements</code>

• Default Parameter: The following template takes an optional reference parameter A as a parameter, with a default value of 10:

<code class="cpp">template<int &A = 10>
struct SillyExample {
    // ...
};

SillyExample<flag> test; // Initializes 'flag' to 10</code>

Conclusion

Non-type template parameters are a powerful tool in C that allow for customizable and reusable code. They enable compile-time configuration of templates, provide default values for parameters, and contribute to improved code design.

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