c++ - 2d STL vector typeid -


i have various 2d vectors , want query differing types @ runtime.

it appears possible on "empty" vector, e.g.:

vector<vector<float> > myvec; cout << (typeid(myvec[0][0]).name() << endl;

the above returns "float" although expecting exception i've not pushed elements.

is luck when accessing memory @ [0][0] without bounds checking or iterator succeeds? or vector allocate baseline storage when declared?

since float not have virtual methods, compiler can evaluate typeid(some_float_object) statically without looking @ actual expression, static type. according section 5.2.8 of c++ standard (current c++0x draft), compiler not allowed evaluate expression.


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