c++ - default values and negative indexes when creating vector class -

i decided train myself in classes , build vecofint class, resemble vector container several methods.

my program works great, have found not entirely understand principles.

1. default values:

here class:

class vecofint { public:     vecofint() : vec(new int[size1]) { zeros(); }     ~vecofint() { delete vec; }     vecofint(const int size) { set(size); vec = new int[size1]; zeros(); }     vecofint& operator = (const vecofint& other) { vec = other.vec; size1 = other.size1; vec1 = other.vec1; }     vecofint(const vecofint& other) : vec(other.vec), size1(other.size1), vec1(other.vec1) {}     int getin(const int a) { return vec[a]; }     int get() { return size1; }     void set(const int a) { size1 = a; }     void setin(const int a, const int val) { vec[a] = val; }     int* pushback(const int val);     int* pushfront(const int val);     int* it;     void resize();      void resize1();     void zeros() {int * = vec; fill(i, + size1, 0);}     void print() { copy(vec, vec + size1, ostream_iterator<int>(cout, "\n")); } private:     int size1 = 32;     int* vec;     int* vec1; }; 

as can see assign values of created vector 0. 2 reasons:

a) have found

vector <int> a(10); copy(a.begin(), a.end(), ostream_iterator<int>(cout, " ")); 

prints 0 0 0 0 0 0 0 0 0 0;

b) need default values implement pushback method:

int* vecofint::pushback(const int val) {     int k = 0;     int* = vec;     while (*it!=0) {         if (k == size1) {             resize();             = vec+size1/2;         }         ++k;         ++it;     }         vec[k] = val;         return vec; } 

and use zeros. not that, because means cannot use 0 not-default values.

first question:

how can avoid these assignments zeros, still have basic values iterate through vector? or maybe there other methods on how iterate through newly created space?

2) negative indexes

suppose trying, mistake, access negative index.

second question:

what program should write in case? error?

i have found in real vector nothing happens, @ least until destructor called.