variable-sized object may not be initialized
arrays, c++
Solution
Isn't the value of `N` known at compile time?
No. At the time `aMemberFunction` is compiled, the compiler does not now what `N` is, since its value is determined at run-time. It is not smart enough to see that there is only one constructor, and assumes that the value of `N` could be different than 5.
Problem
I have a class like this ``` class aClass { public: aClass() : N(5) {} void aMemberFunction() { int nums[N] = {1,2,3,4,5}; } private: const int N; }; ``` The testing code is ``` int main() { aClass A; A.aMemberFunction(); const int N = 5; int ints[N] = {5,4,3,2,1}; return 0; } ``` When I compile (g++ 4.6.2 20111027), I get the error ``` problem.h: In member function ‘void aClass::aMemberFunction()’: problem.h:7:31: error: variable-sized object ‘nums’ may not be initialized ``` If I comment out the line with `int nums[N]` I don't get a compilation error, so the similar code for the `ints` array is fine. Isn't the value of `N` known at compile time? What's going on? Why is `nums` considered a variable-sized array? Why are the arrays `nums` and `ints` handled differently?