For what value of the constant $c$ is the function $f$ continuous on $( -\infty , \infty )$ where $$f( x ) = \begin{cases} c & \text{ if } x=0 \quad \quad \\ x\sin\frac{1}{x} & \text{otherwise } \end{cases}$$

$c$ =

Hint: Compute $\displaystyle \lim_{x\rightarrow 0} f(x)$?