How to use ctype.h functions

The following codes shows how to use isdigit(), isalpha(), isalnum(), isxdigit(), isspace(), iscntrl(), ispunct(), isprint(), isgraph(),
#include<stdio.h>
#include<ctype.h>
int main()
{int i;
char f;
printf("enter character\n");
scanf("%c",&f);
i=isdigit(f);
if(i==0)printf("not digit\n");else printf("is digit\n");
i=isalpha(f);
if(i==0)printf("not alpha\n");else printf("is alpha\n");
i=isalnum(f);
if(i==0)printf("not digit or aplha\n");else printf("is digit or alpha\n");
i=isxdigit(f);
if(i==0)printf("not xdigit\n");else printf("is xdigit\n");
i=isspace(f);
if(i==0)printf("not space\n");else printf("is space\n");
i=iscntrl(f);
if(i==0)printf("not cntrl\n");else printf("is cntrl\n");
i=ispunct(f);
if(i==0)printf("not punct\n");else printf("is punct\n");
i=isprint(f);
if(i==0)printf("not print\n");else printf("is print\n");
i=isgraph(f);
if(i==0)printf("not graph\n");else printf("is graph\n");
}