$\begin{array}{1 1} \int \overrightarrow{B} . \overrightarrow{dl}= \pm 2 \mu_o I \\ \text{The value of $\int \overrightarrow{B}. \int \overrightarrow{dl}$ is independent of sense of C} \\ \text{These may be point on C where $\overrightarrow{B}$ and $ \overrightarrow{dl}$ are perpendicular} \\ \text{variable everywhere on C} \end{array} $