Definition of continuity is that for small changes in the input there should be small changes in the output.Otherwise the function is discontinuous.
So,with this definition we can say that a constant function is discontinuous.
Another definition for continuity is that: "L.H.L = R.H.L = value of function at that point"
with this definition we can say that constant function is continuous .
So,why am I facing a contradiction ,I wonder if my understanding is wrong about the continuity of a function.
Your first definition is wrong. It should read:
No change is not a large change (which is what Cameron essentially said in jest in his comment).