bool eq = false,    // if A == B
     lt = false,    // if A < B
     gt = false;    // if A > B
double range_lower = B - 0.5;
double range_upper = B + 0.5;

if( (range_lower <= A) && (A <= range_upper))   // check for equality;
    eq = true;
else if (A > range_upper)
    gt = true;
else
    lt = true;