How to initialize Vec3 Array

I have now a new problem?
I want use a vec3-array to store 12 vertices.
But wenn I run this program, I have got warnings:

vec3 vertices[12];
vertices[0] = calcPoint();
vertices[1] = calcPoint();
vertices[11] = calcPoint();

Warnings: x 12 times
Warning C7050 :“vertices[0]” might be used before being initialized.

My Questions are:
1, Did i realy do something wrong?
2, If I was wrong, how can I initialize a vec3 Array like:

vec3 array[12];


vec3 vertices[] = vec3[12](
calcPoint(), calcPoint(), … , calcPoint()