Let $L$ be algebraic curve.
Can we say that, $L$ is a piecewise ${C^\infty }$ curve?
Let $L$ be algebraic curve.
Can we say that, $L$ is a piecewise ${C^\infty }$ curve?
You're thinking of an algebraic curve over the reals?
Then yes, because the singular locus is a subvariety and therefore consists of finitely many points.