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Question

I'm new in using templates in C++, I want to do different things depending on type used between < and > , so function<int>() and function<char>() won't do the same things. How can I achieve this?

template<typename T> T* function()
{
    if(/*T is int*/)
    {
        //...
    }
    if(/*T is char*/)
    {
        //...
    }
    return 0;
}

Answer 1

You want to use explicit specialization of your function template:

template<class T> T* function() {
};

template<> int* function<int>() {
    // your int* function code here
};

template<> char* function<char>() {
    // your char* function code here
};

Answer 2

Create template specializations :

template<typename T> T* function()
{
 //general case general code
}

template<> int* function<int>()
{
  //specialization for int case.
}

template<> char* function<char>()
{
  //specialization for char case.
}

Answer 3

Best practices involves tag dispatch, because specialization is tricky.

Tag dispatch is easier to use quite often:

template<typename T>
T* only_if_int( std::true_type is_int )
{
  // code for T is int.
  // pass other variables that need to be changed/read above
}
T* only_if_int( std::false_type ) {return nullptr;}
template<typename T>
T* only_if_char( std::true_type is_char )
{
  // code for T is char.
  // pass other variables that need to be changed/read above
}
T* only_if_char( std::false_type ) {return nullptr;}
template<typename T> T* function()
{
  T* retval = only_if_int( std::is_same<T, int>() );
  if (retval) return retval;
  retval = only_if_char( std::is_same<T, char>() );
  return retval;
}

Answer 4

template<class T>
T Add(T n1, T n2)
{
    T result;
    result = n1 + n2;

    return result;
}

For In detail understanding of template, go through the below link: http://www.codeproject.com/Articles/257589/An-Idiots-Guide-to-Cplusplus-Templates-Part-1

Answer 5

you can define overloaded functions something like this:

#define INTT  0
#define CHARR 1
template<typename T>
T* function()
{
int type;
type = findtype(T);
//do remaining things based on the return type

}

int findType(int a)
{
return INTT;
}

int findType(char a)
{
return CHARR;
}