Template specialization

Learn type-specific customization with template specialization.

Template specialization

Sometimes a template must behave differently for a specific type. Template specialization provides this. template <> struct Vector<bool> { ... }; is a specialized version for bool.

The empty angle brackets in template <> mean no type parameter remains; this is a full specialization. The general template template <typename T> struct Vector stays as is; the bool specialization overrides it. Vector<int> uses the general template, Vector<bool> uses the specialization.

Why specialize?

A bool vector can pack 8 bools into 1 byte. The general template cannot; it would allocate 1 byte per bool. Specialization provides an optimized version for specific types.

Full specialization is written with template <>. Partial specialization fixes some parameters: template <typename U> struct Vector<U*> is for pointer types. This lesson covers only full specialization. Specialization is used when performance or memory gains matter.

Exercise Write the Vector<bool> specialization

First write the general template: template <typename T> struct Vector { T data; };. Then specialize for bool: template <> struct Vector<bool> { static const int bits = 8; };. In main write std::cout << Vector<bool>::bits << std::endl;.

Show example solution

#include <iostream>

template <typename T>
struct Vector {
    T data;
};

template <>
struct Vector<bool> {
    static const int bits = 8;
};

int main() {
    std::cout << Vector<bool>::bits << std::endl;
    return 0;
}

Test yourself

Match the concept

template <>

Full specialization
Vector<bool>

Special for bool
template <typename T>

General template
Vector<int>

General use

Complete the specialization declaration

template <> struct Vector<____> { static const int bits = 8; };

Show answer

template <> struct Vector<bool> { static const int bits = 8; };

When is template specialization used?
```
// Belirli tür için özel davranış
```
- When custom behavior is needed for a specific type
- Never
- Always
- Only when debugging
Show answer

When custom behavior is needed for a specific type — Specialization is used when a specific type needs custom behavior.

Next lesson: Summary - Template basics

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