CODEWITHSUNDEEP
c++templatestemplate-specializationspecialization
prosseek
prosseek

Reputation: 190659

Partial specialization in c++ template

I have a template class to print out the elements in vector. I have both for pointer and reference version. 

// HEADER
class Util {
...
template <class T>
static void print(const std::vector<T>* vectorArray);

template <class T>
static void print(const std::vector<T>& vectorArray);
...
static void printByteStream(const std::vector<unsigned char>& input);
...
}; 

// BODY
template <class T>
void Util::print(const std::vector<T>* vectorArray)
{
    for (auto i = vectorArray->begin(); i != vectorArray->end(); ++i)
    {
        std::cout << *i << ":";
    }
    std::cout << std::endl;
}

template <class T>
void Util::print(const std::vector<T>& vectorArray)
{
    return Util::print(&vectorArray);
}

template void Util::print(const std::vector<int>* vectorArray);
template void Util::print(const std::vector<std::string>* vectorArray);
template void Util::print(const std::vector<int>& vectorArray);
template void Util::print(const std::vector<std::string>& vectorArray);

I also have a print code for byte stream. 

void Util::printByteStream(const std::vector<unsigned char>& input)
{
    for (auto val : input) printf("\\x%.2x", val);
    printf("\n");
}

I want to teach the C++ compiler that when I call print with T == unsigned char, call the printByteStream with partial specialization.

I added this code in the body.

void Util::print(const std::vector<unsigned char>& vectorArray)
{
    return Util::printByteStream(vectorArray);
}

When compiled, the C++ compiler complains that it can't find matching code. What might be wrong?

error: prototype for 'void Util::print(const std::vector<unsigned char>&)' does not match any in class 'Util'
 void Util::print(const std::vector<unsigned char>& vectorArray)

Upvotes: 0

Views: 173

Answers (1)

aivision2020
aivision2020

Reputation: 629

I think you need to add an empty template

template <>
void Util::print(const std::vector<unsigned char>& vectorArray)
{
    return Util::printByteStream(vectorArray);
}

I have to check. I don't have VS on this computer though.

Upvotes: 2

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