Question

When writing function or class templates, you use a(n) _____________ to specify a generic data type.

Short answer

Answer: Template parameter.

Step-by-step solution

Identifying the term for generic data types

When writing function or class templates, a generic data type can be specified by using a(n) "template parameter." This can be seen as a placeholder for an actual data type, allowing for flexibility and reusability when working with different data types.

Key concepts

Function Templates

Just like a custom-made suit is tailored for a specific person, a function template is a blueprint that allows programmers to create a function that can be customized for different data types. When you use a function template, you don't write code for every single type - instead, you write one template and it can be used for any type specified at the time of calling.

Think of a function template as a kind of mold that shapes dough into various forms - whether you want a cookie or a donut, the mold adjusts accordingly. For example, let's say we have a function max() that compares two numbers and returns the larger one. If we define it using a function template, we could use it for int, float, or even user-defined types like BigInteger, all without writing separate functions for each type.

Here's a simple example of a function template:

template<typename T>T max(T a, T b) { return (a > b) ? a : b;}

This template declares a generic type T, which can be replaced with any data type when the function is called, making your code more flexible and reusable.

Class Templates

Zooming out from functions to entire classes, a class template offers a similar flexibility but on a larger scale. It's comparable to having a master key for different locks - you can access a variety of functionalities with a single key, your template.

With class templates, you define a blueprint for a class that can work with any data type. This makes it possible to create a generic class, like a pair or a container, which operates on the data type specified when you instantiate an object from the class template.

Here's a brief example of a class template for a simple container:

template<typename T>class Container {  T value;public:  void set(T a) { value = a; }  T get() { return value; }};

In this case, T is a placeholder, which will be replaced by an actual data type when an object of Container is created. It means you can have a container holding an int, another holding a string, and yet another holding a std::vector, all using the same class template.

Generic Data Types

At the heart of both function and class templates lies the concept of generic data types. Imagine generic data types as a universal puzzle piece that fits into any puzzle spot, adapting its shape according to the need.

A generic data type, as used in templates, is known as a template parameter. It stands in place for a specific data type when a template is instantiated. For instance, if you have a function template to find the maximum of two values, the generic data type allows that function to work whether those values are integers, doubles, or even strings - all determined by the template argument provided during function call.

A key benefit of using generic data types in templates is that they promote code reusability and flexibility. Instead of writing multiple versions of the same function or class for different data types, you can write a single, general version that adapts to the given context. This not only saves time but also reduces errors and inconsistencies in the codebase.