Introduction to Template Specialization

A general template works for any data type. However, certain types might require special treatment. For example, if you're implementing a function that behaves differently for int and std::string types, template specialization allows you to define a different version of the template for each type.

main.cpp


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#include <iostream>

template<typename T>
T square(T value) {
    return value * value;
}

int main()
{
    std::cout << square<int>(25);
    std::cout << square<std::string>("5");
}

If you run the code above, you will encounter an error. This occurs because std::string does not support the * operator. Therefore, it is necessary to inform the compiler about how to handle a std::string passed as a parameter.

How Templates Work Under the Hood

For now, you are just grasping the basics of templates, specifically function templates. You have learned how to create them, use parameter lists, and call the functions with different data types. You might wonder why, in this case, we wouldn't just overload functions for all available numeric types in C++. While this approach could work for this example, it’s important to remember that templates are a much more powerful tool.

main.cpp


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#include <iostream>

struct myStruct {};
class myClass {};

template<typename T>
void TemplateFunction() { std::cout << typeid(T).name() << std::endl; }

int main()
{
    TemplateFunction<myClass>();
    TemplateFunction<myStruct>();
}

Templates can accept any data type, including user-defined types. In contrast, relying solely on function overloading would require creating a new function for each type, making updates cumbersome and error prone. Therefore, we can't rely on function overloading alone and must use template specializations to address issues like those in the square template function.

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C++ Templates

1. Creating First Template

Introduction to C++ Templates Basic Syntax of Templates in C++Creating Your First Template in C++Working with Multiple Typenames in Templates Naming Conventions

2. Templates Usage

Typename Parameter as a Return Type Implicit and Explicit Type Specification Non-type Template Parameters

3. Class Templates

Introduction to Class templates Template Classes and STL Templates with Default Type Parameters Class Template Argument Deduction

4. Template Specialization

Introduction to Template Specialization How to Use Template Specialization Partial Template Specialization Template Constraints Overview

Introduction to Template Specialization

main.cpp


              123456789101112
            
#include <iostream>

template<typename T>
T square(T value) {
    return value * value;
}

int main()
{
    std::cout << square<int>(25);
    std::cout << square<std::string>("5");
}

How Templates Work Under the Hood

main.cpp


              12345678910111213
            
#include <iostream>

struct myStruct {};
class myClass {};

template<typename T>
void TemplateFunction() { std::cout << typeid(T).name() << std::endl; }

int main()
{
    TemplateFunction<myClass>();
    TemplateFunction<myStruct>();
}

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 4. Kapitel 1