why was my version of ungetch() and getch() wrong?

Question

i'm searching for a long time on net. but no use. please help me.

/* getch and ungetch to handle EOF Character In all the ungetch and getch 
* functions written so far, the buf is declared as char buf[BUFSIZ]. 
* Changing this to int buf[BUFSIZ] enable it to handle EOF. As EOF is an 
* integer declared in stdio.h having the value -1 */ 
#include<stdio.h> 
#define BUFSIZE 100 
int getch(void); 
void ungetch(int c); 

char buf[BUFSIZE]; /* buffer for ungetch */ 
int bufp = 0; /* next free position in buf */ 
int main(void) 
{ 
    int c; 

    c = '*'; 

    ungetch(c); 
    while((c=getch())!=EOF) 
        putchar(c); 
    return 0; 
} 

/* getch: get a (possibly pushed back) character */ 
int getch(void) 
{ 
    return (bufp > 0) ? buf[--bufp] : getchar(); 
} 

/* ungetch: push a character back onto the input */ 
void ungetch(int c) 
{ 
    if (bufp >= BUFSIZE) 
        printf("ungetch: too many characters \n"); 
    else 
        buf[bufp++] = c; 
}

i wanted to use pointer to achieve same effect. But i failed( wrong codes are as follows). Bufp = buf has a error.The error was that Bufp: different level between the indirection of int and char*. In my limited experience with pointer, the type of pointer Bufp is char* ,it points to char data type.char buf[BUFSIZE]; means buf[] is a array of characters. If what i said was right, why did the problem appear? was there something i ignored?

char buf[30];
char *Bufp;

Bufp = buf;
int getch(void)
{
    return (Bufp >= buf) ? *(--Bufp) : getchar();
}

void ungetch(int c)
{
    if (c != EOF)
        *Bufp++ = c;
    else
        printf("no space\n");
}