Learn Type Template Parameter With A Default In C++

One of the great features of modern C++ is the ability to define templates. A template is a simple and very powerful statement in C++ that defines the operations of a class or function. In this article, we will explain type parameters with a default for templates in C++. You can download C++ here and use a professional C++ IDE and compiler to try things out for yourself. 

What is a template in C++?

A template is a very powerful statement in C++ that simply defines the operations of a class, a function, an alias, or a variable. It lets the user apply the same template on different types to increase code reuse. Templates are like macros in C++, except the compiler checks the types used before the template is expanded. In the compilation mechanism of a template in C++, the source code contains only a template for a function or class, but when it is compiled, the same template can be used on multiple data types.

Here is the syntax of a template:

What are type parameters for templates in C++?

A template has at least one template parameter.

The parameters of a template can be,

• type template parameter,
• non-type template parameter,
• template template parameter (a template used as a parameter).

A type template parameter (typename or class) is a type parameter key provided within a template parameters list and it is a typename or class. Thus, user may use different type names or classes for the different declarations with templates. Here is a syntax for a template that has type parameter,

What is type template parameter with a default in C++?

A type template parameter (typename or class) is a type parameter key provided within a template parameters list, and it is a typename or class. The user may use different type names or classes for the different declarations with templates. Here is a syntax for a template that has type parameter,

Sometimes, when we declare a template we use a type template parameter with a default. In this way, you can easily use templates with default option, or you can define your class name.

Here is the syntax for a C++ template parameter with a default.

A type parameter can be one of the following types,

• typename
• class
• concept (since C++20)

For example, we can declare a template with a void default as below,

name is optional so if you don’t need class name in your template you can use without class name as below too,

Is there a C++ example of a type template parameter with a default?

When we create a template with a type parameter, we can define its default type (for example a void, or a class, or a typename) as shown below.

Here is an example of a C++ template parameter with a default.

Is there a C++ VCL example of a type template parameter with a default?

In C++ Builder, you can use the example above as console application.

Here is a full C++ VCL console example to the ‘template parameter with a default’ in C++ Builder.

Here is a full Windows VCL Application C++ Builder example of a template parameter with a default.

Is there a C++ FMX example of a type template parameter with a default?

Here is a full C++ FMX console example of a template parameter with a default in C++ Builder.

Here is a full Windows FMX Application C++ Builder example of a C++ template parameter with a default.

C++ Builder is the easiest and fastest C and C++ IDE for building simple or professional applications on the Windows, MacOS, iOS & Android operating systems. It is also easy for beginners to learn with its wide range of samples, tutorials, help files, and LSP support for code. RAD Studio’s C++ Builder version comes with the award-winning VCL framework for high-performance native Windows apps and the powerful FireMonkey (FMX) framework for cross-platform UIs.

There is a free C++ Builder Community Edition for students, beginners, and startups; it can be downloaded from here. For professional developers, there are Professional, Architect, or Enterprise versions of C++ Builder and there is a trial version you can download from here