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Variable length arrays are also known as runtime sized or variable sized arrays. The size of such arrays is defined at run-time. Variably modified types include variable length arrays and pointers to variable length arrays. Variably changed types must be declared at either block scope or function prototype scope.
A dynamic array expands as you add more elements.
To resize an array you have to allocate a new array and copy the old elements to the new array, then delete the old array.
I'd like to use boost::array as a class member, but I do not know the size at compile time. I thought of something like this, but it doesn't work:
int main() {
boost::array<int, 4> array = {{1,2,3,4}};
MyClass obj(array);
}
class MyClass {
private:
boost::array<int, std::size_t> array;
public:
template<std::size_t N> MyClass(boost::array<int, N> array)
: array(array) {};
};
The compiler, gcc, says:
error: type/value mismatch at argument 2 in template parameter list for
‘template<class _Tp, long unsigned int _Nm> struct boost::array’
error: expected a constant of type ‘long unsigned int’, got ‘size_t’
Which obviously means that one cannot use variable-sized arrays as class members. If so, this would negate all the advantages of boost::array over vectors or standard arrays.
Can you show me what I did wrong?
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