$[10]$ Textbook, Ch$.2,$ Exercise $6.$ C program can access an array element by dereferencing a pointer $($e$.$g$.,*$p$)$ or using a subscript operation $[]($e$.$g$.,$ a $[5]).$ For example,

int arr$[5]=\{10,20,30,40,50\}$;

int $*$ptr $-$ arr;

Both $*($ptr$+2)$ and arr $[2]$ represent the $3^{rd}$ array element, i$.$e$.,30.$ Rewrite the following function, and use pointers instead of an array subscript operator.

int sum$($int arr$[],$ int $n)$

$\{$

int sum $=0,i$;

for $)=0$;$i$

sum $+=$arr$[i]$;

return sum;

$\{$