Program to convert a upper case character into lower case character using function in C

/* upper to lower */
# include <stdio.h>
void upper-to-lower (char) ;
void main ()
{
char ch ;
printf ("\n Enter a upper case character:") ;
scanf ("%d", & ch) ;
upper-to-lower (ch) ;
getch () ;
}
void upper-to-lower (char ch)
{
ch = ch+32 ;
printf ("%c", ch) ;
}