declaring inside an if...

alright, i know this is a C++ question, but i like u guys here, and you help quickly =P
alright, i have a program i have to make for school… but im stuck, i have a menu (cout << enter number…; cin >> choice;" right, and i have an if right after that for which choice they made…
i have a class called "MyVec, and i have overloaded it, so i can pass MyVec Vect(); MyVec Vect(x); MyVec Vect(x,y);… this is based off the choice (1,2,3)…
if its one, i want to just go “MyVec Vect();” if 2: “MyVec Vect(x)” etc.
the problem is, when i declare them INSIDE the if statements, then they are LOCAL TO THE IF!!! in other words, i cant pass them anyplace else…
anyone wanna help me?

MyVec *vec;

case 1:
vec = new MyVec();
case 2:
vec = new MyVec(bleh);