Re: typedef float float4[4]; std::vector<float4>; does not compile, why?

From:
"Chris M. Thomasson" <no@spam.invalid>
Newsgroups:
comp.lang.c++
Date:
Tue, 19 May 2009 10:49:19 -0700
Message-ID:
<guureq$2f7t$1@news.ett.com.ua>
"Chris M. Thomasson" <no@spam.invalid> wrote in message
news:guuqts$2evh$1@news.ett.com.ua...

"Brian Cole" <coleb2@gmail.com> wrote in message
news:652f9330-ecf8-4b0b-bf5a-9ee62d8845b0@d25g2000prn.googlegroups.com...

The following code will not compile in gcc 4.3.2 on Ubuntu 8.10

#include <vector>

typedef float float4[4];

int main()
{
  std::vector<float4> vals;
}

I get the following compilation error:


Try something like this:
_____________________________________________________________________
[...]> std::size_t c1;
 std::vector<float4>::iterator i;

 for (i = v.begin(), c1 = 0; i != v.end(); ++i, ++c1) {
   for (std::size_t c2 = 0; c2 < float4::SIZE; ++c2) {
     std::printf("v[%u][%u] == %u\n", c1, c2, v[c1][c2]);
   }
 }

 return 0;
}
_____________________________________________________________________

[...]


Ummm.... I don't know why I did the iteration that way. Perhaps I should
actually use the damn iterator object `i'!!! Here, let me try again:
_____________________________________________________________________
#include <cstdio>
#include <cstddef>
#include <cassert>
#include <vector>

template<typename T, std::size_t T_size>
class array {
  T m_buffer[T_size];

public:
  enum constant {
    SIZE = T_size
  };

  T& operator [] (std::size_t size) {
    assert(size < T_size);
    return m_buffer[size];
  }

  T const& operator [] (std::size_t size) const {
    assert(size < T_size);
    return m_buffer[size];
  }

  T* get() {
    return m_buffer;
  }

  T const* get() const {
    return m_buffer;
  }
};

typedef array<unsigned, 4> float4;

int main() {
  std::vector<float4> v;

  v.push_back(float4());
  v.push_back(float4());

  v[0][0] = 1;
  v[0][1] = 2;
  v[0][2] = 3;
  v[0][3] = 4;

  v[1][0] = 5;
  v[1][1] = 6;
  v[1][2] = 7;
  v[1][3] = 8;

  std::size_t c1;
  std::vector<float4>::const_iterator i;

  for (i = v.begin(), c1 = 0; i != v.end(); ++i, ++c1) {
    for (std::size_t c2 = 0; c2 < float4::SIZE; ++c2) {
      std::printf("v[%u][%u] == %u\n", c1, c2, (*i)[c2]);
    }
  }

  return 0;
}
_____________________________________________________________________

There... That's better. I mean, the first posted program works, but its
retarded! Sorry about that.

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