Can Templated C Classes Be Split into Separate Header and Implementation Files?

Is Splitting Templated C Classes into Separate .hpp and .cpp Files Feasible?

When attempting to compile a templated C class across separate header (.hpp) and implementation (.cpp) files, you may encounter linking errors. Consider the following code:

// stack.hpp
template <typename Type>
class stack {
    // ...
};

// stack.cpp
template <typename Type> stack<Type>::stack() {
    // ...
}

// main.cpp
#include "stack.hpp"
stack<int> s;

Compilation fails with "undefined reference" errors for the template class methods. While possible, moving all method implementations into the header file is not an ideal solution.

Why Separate Compilation Fails for Template Classes

The issue stems from the fact that template classes are not fully defined at compile time. The compiler generates code for specific instantiations based on the template parameters provided. Without the template parameters, the compiler cannot generate memory layout and code for the methods in the implementation file.

Alternative: Separating Data Structures and Algorithms

To hide implementation details while maintaining separation, consider splitting data structures from algorithms. Template classes should primarily define data structures, while non-templated algorithm classes operate on or use them. This approach effectively hides valuable implementation details without the need for separate implementation files for template classes.

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