If c is a character variable that contains a digit, what does the following function return?

int digit$\_$to$\_$int$($char c$)$

$\backslash \{$

return $($int$($c$)-$ int$(\text{'}0\text{'}))$;

$\backslash \}$

the ASCII value of $\backslash ($ c $\backslash )$

the character value of $\backslash ($ c $\backslash )$

the integer equivalent of the digit stored in c

none of these