Question

I was wondering if it is possible to declare an array (size not known at this time), as a private member of a class and later set the size in the constructor of the class. For example:

class Test { int a[]; public: Test(int size); };  Test::Test(int size) { a[size];   // this is wrong, but what can i do here? } 

Is this possible or should I use dynamic arrays? Thanks!

Answer 1

No this is not possible. Array declarations in headers must have constant sized value. Otherwise it’s impossible for constructs like ‘sizeof’ to function properly. You’ll need to declare the array as a pointer type and use new[] in the constructor. Example.

class Test {      int *a; public:     Test(int size) {        a = new int[size];     }     ~Test() { delete [] a; } private:     Test(const Test& other);     Test& operator=(const Test& other); };