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  • What compiler are you using? The array syntax compiles and runs fine with g++ 4.6.4 and 4.7.3. I'm just getting a warning on the last ] before the = that "value computed is not used" or "statement has no effect". However, if I use g++ 4.8.1 (supposedly fully c++11 compliant), it throws errors on n and o not being constant "array size in operator new must be constant", and points to the last ] in the line.
    – jbo5112
    Commented Oct 1, 2013 at 4:59
  • @cmaster double (*in)[m][n] = (double (*)[m][n])new double[k*m*n]; doesn't work too. I'm getting C2057, C2540 errors on n because it isn't known at compile time. I don't understand why I can't do it, because memory allocated properly and it's only pointers to handle this memory conveniently. (VS 2010)
    – user1234567
    Commented Dec 14, 2014 at 11:30
  • 3
    @user3241228 gcc fooled me when I wrote this: supplying -std=c++11 is not enough to switch on strict standard conformance, -pedantic-errors is required as well. Without the later flag, gcc happily accepts the cast, even though it is indeed not according to the C++ standard. With what I know now, I can only advise to fall back to C when doing stuff that's heavily reliant on multidimensional arrays. C99 is just much more powerful in this regard than even C++17 will be.
    – cmaster - reinstate monica
    Commented Dec 14, 2014 at 13:46
  • @cmaster dynamically allocated VLAs are syntactic sugar anyway... they're good in C because there's nothing else, but C++ has better syntactic sugar :)
    – M.M
    Commented Sep 30, 2015 at 0:08
  • 3
    @M.M Pity that C++ does not have syntactic sugar for a true, consecutive multidimensional array allocated on the heap with sizes that are only known at runtime. As long as you don't need this, C++ syntactic sugar is fine. But when you need all the above, even FORTRAN beats C++...
    – cmaster - reinstate monica
    Commented Sep 30, 2015 at 5:24