Limited-length string class

Question

Is there a limited-length string class around? I've searched a little on the net and didn't find anything. I'm interested in a class that limits (possibly at compile time) the length to 255, so marshalling the string's length only requires one byte.

Answer 1

You can make a wrapper arount std::string and force the length limit

Answer 2

The issue of using a byte to address elements of the string probably means you'll need to write your own class with a [] operator and iterator that accepts / uses a uint8_t for indexing.

Depending on how you write it, some things you'll be able to enforce at compile time. For instance you could use a template argument to define the type you're going to use for indexing string elements.

Answer 3

With C++0x you can use static_assert

#include <type_traits>
int main (void)
{
   char test[] = "test";
   static_assert(sizeof (test) <= 5, "Error: String too long!");
   return 0;
}

Compile with:

g++ -std=c++0x test.cc

If you are not able to use C++0x. Then you can use the method described here:

namespace static_assert
{
    template <bool> struct STATIC_ASSERT_FAILURE;
    template <> struct STATIC_ASSERT_FAILURE<true> { enum { value = 1 }; };

    template<int x> struct static_assert_test{};
}

#define COMPILE_ASSERT(x) \
    typedef ::static_assert::static_assert_test<\
        sizeof(::static_assert::STATIC_ASSERT_FAILURE< (bool)( x ) >)>\
            _static_assert_typedef_

int main (void)
{
  char test[] = "test";
  COMPILE_ASSERT(sizeof (test) <= 5);
  return 0;
}