One request I got multiple times is to have more example transformations available. In

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What about recursive templates? <div class="highlight highlight-source-c++ notrans

Hello, there is now an <a href="https://cppinsights.io/examples.html

Providing more demo code to show in C++ Insights about cppinsights HOT 4 CLOSED

andreasfertig commented on May 14, 2024

Providing more demo code to show in C++ Insights

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Comments (4)

weliveindetail commented on May 14, 2024

In addition to the existing Range-based For Loop example, one for C++17 Structured Bindings may be a good candidate, e.g:

#include <cstdio>
#include <tuple>

auto mypair() {
  return std::make_tuple("hello", 1);
}

int main() {
  auto [c, n] = mypair();
  printf("c=%s, n=%d\n", c, n);
}

This emits:

int main() {
  auto __mypair9 = mypair();
  std::tuple_element<0, std::tuple<const char *, int> >::type&& c = get<0ul>(__mypair9);
  std::tuple_element<1, std::tuple<const char *, int> >::type&& n = get<1ul>(__mypair9);
  
  printf("c=%s, n=%d\n", c, n);
}

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weliveindetail commented on May 14, 2024

#include <cstdio>
#include <string>
#include <tuple>
#include <vector>

template <typename Tuple_t>
void fillTuples(std::vector<Tuple_t> tuples) {
  tuples.emplace_back("hello", 1);
}

int main() {
  std::vector<std::tuple<std::string, int>> tuples;
  fillTuples(tuples);
    
  for (auto [s, n] : tuples) {
    printf("c=%s, n=%d\n", s.c_str(), n);
  }
}

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Amomum commented on May 14, 2024

What about recursive templates?

#include <cstdio>
#include <vector>

template<int n>
struct A
{
  static const auto value = A<n-1>::value+n;
};

template<>
struct A<1>
{
	static const auto value = 1;
};


int main()
{
      printf("c=%c\n", A<5>::value);
}