


Why Do I Get 'Undefined Reference to' Errors for Template Class Constructors, and How Can I Fix Them?
Dec 12, 2024 pm 07:58 PM"Undefined Reference to" Template Class Constructor [Duplicate]
The compiler error "undefined reference to..." for template class constructors signifies a lack of explicit instantiation instructions for the specific template classes used in the program. This issue arises because the compiler doesn't automatically compile template code until it's explicitly required.
Solution 1: Explicit Template Instantiation
Append explicit template instantiation statements to the end of the implementation file (cola.cpp in this case):
template class cola<float>; template class cola<string>;
Additionally, include the following lines in nodo_colaypila.cpp:
template class nodo_colaypila<float>; template class nodo_colaypila<std::string>;
This forces the compiler to compile the required template classes.
Solution 2: Include Implementation in Header File
Move the implementation code from cola.cpp and nodo_colaypila.cpp into cola.h and nodo_colaypila.h, respectively. This ensures the availability of function definitions in all translation units using the template classes.
Pros and Cons of Each Solution:
-
Solution 1:
- Pro: More efficient as it only compiles the necessary template instances.
- Con: Requires manual instantiation for each desired template class.
-
Solution 2:
- Pro: More convenient and flexible, as it allows for future template class instantiations.
- Con: Potentially slower compilation due to duplicate code generation for each translation unit.
Other Typos in the Code:
- Mismatched pointer syntax in the cola.h declaration:
nodo_colaypila<T><T>* ult, pri;
should be:
nodo_colaypila<T>* ult, *pri;
- Missing #endif at the end of nodo_colaypila.h.
- Default parameter for nodo_colaypila constructor should be defined in the header file, not the implementation file.
The above is the detailed content of Why Do I Get 'Undefined Reference to' Errors for Template Class Constructors, and How Can I Fix Them?. For more information, please follow other related articles on the PHP Chinese website!

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