Fill string of 100 labels that are selected

I have 100 checkbox and I want to fill a string with the ones that are already selected and I tried the following:

CheckBox[] box = new CheckBox[2];
box[0] = CheckBox1;
box[1] = CheckBox2;
for(int i=0;i<box.Length;i++)
{
    soci = soci + "\n" + box[i].Text;
}