How to Explicitly Instantiate Template Functions in C ?

Explicit Instantiation of Template Functions

In C , template functions provide a way to define operations that can operate on different types. Sometimes, it becomes necessary to explicitly instantiate a template function without calling it directly. This can be useful in situations where the compiler cannot automatically infer the template arguments.

Consider the following example:

template <class T> int function_name(T a);

To explicitly instantiate this function for integers, one might attempt to write:

template int function_name<int>(int);

However, this approach results in the following errors:

error: expected primary-expression before 'template'
error: expected `;' before 'template'

To correctly explicitly instantiate the function, use the following syntax:

template <typename T> void func(T param); // definition

template void func<int>(int); // explicit instantiation

It's important to note that this code performs explicit instantiation, not specialization. The syntax for specialization differs slightly:

template <typename T> void func(T param); // definition

template <> void func<int>(int); // specialization

Explicit instantiation ensures that the code for the instantiated template function is generated by the compiler, making it available for use without the need to directly call the template function with the appropriate type arguments.

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