The swap function below contains an error. What is it$?$

void, swap $($int $x,$ int $y)$

$\{$

int temp $=x$;$x=y$;$y=$ temp;

$\}$

It is not legal to have three statements on a single line

Both parameter variables must be passed by reference

The array being sorted must be a parameter variable

The swap is not correctly implemented by the assignment statements