**Use of Class Template Requires Template Argument List**
Class templates are a powerful feature of C++ that allow you to define a class with generic types. However, using a class template requires a template argument list. In this article, we will discuss the use of class template requires template argument list error and how to fix it.
When you use a class template, you must provide a template argument list that specifies the types to use for the template parameters. If you fail to provide a template argument list, you will get a compiler error that says “use of class template requires template argument list”.
This error occurs because the compiler cannot deduce the template arguments from the function arguments. To fix this error, you need to provide the template arguments explicitly. For example:
How to Fix the Use of Class Template Requires Template Argument List Error
The easiest way to fix the use of class template requires template argument list error is to provide the template arguments explicitly. For example:
template <typename T>
class MyClass {
public:
MyClass(T arg) {}
};
int main() {
MyClass<int> myObject(42);
return 0;
}
In this example, we provide the template argument list <int> when we create an instance of the MyClass class. This tells the compiler to use int as the type for the template parameter T.
Another way to fix this error is to use type deduction. C++17 introduced class template argument deduction, which allows the compiler to deduce the template arguments from the function arguments. For example:
template <typename T>
class MyClass {
public:
MyClass(T arg) {}
};
int main() {
MyClass myObject(42);
return 0;
}
In this example, the compiler deduces that the template argument T should be int based on the argument 42.
Why Use Class Templates?
Class templates are a powerful feature of C++ that allow you to define a class with generic types. This means that you can write a single class that works with many different types. For example, you could write a vector class that works with integers, doubles, or any other type.
Class templates are used extensively in the C++ Standard Library. For example, the vector, list, and map containers are all implemented as class templates.
Conclusion
The use of class template requires template argument list error is a common error that occurs when you use a class template without providing a template argument list. To fix this error, you need to provide the template arguments explicitly or use type deduction. Class templates are a powerful feature of C++ that allow you to define a class with generic types.
FAQ
What is a class template?
A class template is a C++ feature that allows you to define a class with generic types. This means that you can write a single class that works with many different types.
What is a template argument list?
A template argument list is a list of types that you provide when you create an instance of a class template. The template argument list specifies the types to use for the template parameters.
What is the use of class template requires template argument list error?
The use of class template requires template argument list error occurs when you use a class template without providing a template argument list. This error occurs because the compiler cannot deduce the template arguments from the function arguments.
