CODEWITHSUNDEEP
c++c++14
Bart
Bart

Reputation: 1580

Templated return type based on paramter type

The following function is to return the signed version of its parameter. How would I do that with just one template parameter?

template<class UINT_TYPE>
INT_TYPE function_x(const UINT_TYPE n) 
{
  static_assert(std::is_same<UINT_TYPE, uint32_t>::value || 
                std::is_same<UINT_TYPE, uint64_t>::value, 
                "Wrong type passed.");

  return static_cast<INT_TYPE>(n);
}

It is possible to use two template parameters with a default value but this is not preferred.

template<class UINT_TYPE, class INT_TYPE = typename std::make_signed<UINT_TYPE>::type>

If there is any way to do this neatly your ideas are appreciated.

Upvotes: 0

Views: 72

Answers (1)

Brian Bi
Brian Bi

Reputation: 119587

You can deduce the return type:

template <class UINT_TYPE>
auto function_x(const UINT_TYPE n) {
    // ...
    return static_cast<std::make_signed_t<UINT_TYPE>>(n);
}

Upvotes: 4

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