Re: Question about arrays..
Frederick Gotham wrote:
kiddler posted:
I'm sorta new to the C++ syntax.
I know that arrays can be delcared like so:
int a[]={1,2,3,4};
but what if I want the array to be a global, and then set the length
and value inside a method?
like in java, you can do:
int a[];
void main()
{
a=new int{1,2,3,4};
}
How do I do that in C++?
std::vector would probably be the way to go.
Or if you're feeling creative. . .
template<class T>
class Array {
private:
T *pNC;
unsigned lenNC;
public:
T * const p;
unsigned const &len;
Array() : p(pNC), len(lenNC) {}
Neither 'pNC' nor 'lenNC' are initialised. Initialising other members
with their values (indeterminate, BTW), is very dangerous.
void Allocate(unsigned const quantity)
{
lenNC = quantity;
pNC = new T[len];
This doesn't seem to do anything with 'p'. What is 'p' for, then?
}
void Deallocate()
{
delete [] pNC;
}
};
Array<int> a;
int main()
{
a.Allocate(4);
a.p[0] = 1; a.p[1] = 2; a.p[2] = 3; a.p[3] = 4;
Undefined behaviour. You're dereferencing an uninitialised pointer.
...
a.Deallocate();
}
V
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