What Are C++ Templates?
Essentially, a template in C++ can be defined as a “feature” that enables a function or a class to be written regardless of the data type which is used. Instead of writing a new version for every different type of data, you write a new template and that works regardless of whether you are passing an `int`, `float`, or any other type such as user-defined types. Generic programs, as mentioned above, allow you to write templates that are data type agnostic. The codesusion of data types provides a more concise, reusable, and maintainable codebase overall.In programming, templates provide great versatility as they offer the ability to use any data type without losing type safety. This is achieved due to the encapsulation of type checking at the compile-time making sure the template works as intended.
Types of C++ Templates
In C++, function templates and class templates are the two primary types of templates available. Both of them allow the design of functions or classes that will work with any data type but their uses differ.1. Function Templates:
By employing a function template, one can create a single function that serves the purpose of all of the overloaded functions needed to accommodate all possible data types a single function can work with. Thus, one template is written while the compiler takes care of fulfilling the function needed by the client based on the parameters passed in.It becomes evident that the standard procedure of writing several functions to add floats, doubles and even integers to one single array of type inline would not work. Alongside function templates however the generic function can be written once as required and one can let the compiler carry out further actions.
2. Class Templates:
A generic class template enables the individual to define a class without adding in restrictions of specific data types, meaning it works like a function template which is only used for designing classes intended to contain or process some specific type of data. An example of a class template is when creating a linked list for data types, integers, floats or even complex objects.The Functionality of C++ Templates
In comparison to most complex systems, C++ uses templates which are simple yet effective. To enforce a function as a template, the `template` keyword is employed with it. The standard syntax for function templates is defined as such:cpp
template T add(T a, T b) {
return a + b;
} 
Also, when it comes to class templates, the translation is done using `template` along with the class:
cpp
template class Box {
private:
T value;
public:
Box(T v) : value(v) {}
T getValue() {
return value;
}
}; Advantages of Using Templates
Equally, templates are not only concerned about the codes being clean, but there is more to them because they save a lot of time and are quite adaptable when one has to work on a project.1. Code Reusability:
Repetitive code can be reduced through the use of templates. One generic function or class template works with a comprehensive matrix which saves on the repetitive codes and the requirement to overload or design different functions, or classes for different types.2. Type Safety:
Templates are type-safe, meaning that they enforce type checking at compile-time. This ensures errors are caught early and prevents runtime errors related to type mismatches.3. Performance:
Templates are evaluated at compile-time, meaning no performance degradation is experienced during fetches. This is distinct from other ways of achieving generic programming, like using void pointers or dynamic polymorphism, which leads to runtime congestion.4. Flexibility and Extensibility:
A template changes the method definition of class and function objects, adding a capability to boost already existing code. A new class or function is called out for, which possesses an additional and unlike type, and it obtains this by simply calling the template.Specialization of Templates
There are instances when a generalized template is not sufficient and it requires some adjustment. Such adjustments are called template specializations. They help in achieving what is needed by allowing to present a different implementation for a certain type.Say, we have a function which has a generic template that is applicable for all types, but when it is a `char` or a `string` type, we want it to have different behavior. That is what template specialization is used for.
Specialization can be two types: full specialization and partial specialization. A full specialization defines dissimilar behavior for a certain type while, in partial specialization, behavior for a certain category of types, say, certain classes is defined.
