Exercise 4-8. Suppose that there will never be more than one character of pushback. Modify getch and ungetch accordingly.

Exercise 4-8. Suppose that there will never be more than one character of pushback. Modify getch and ungetch accordingly.

/* getch */

char buf = 0;

int getch(void) // get a (possibly pushed-back) character  

{

    int c;

    if(buf == 0)

        c = getchar();

    else

        c = buf;

    buf = 0;

    return c;    

}

/* ungetch */

void ungetch(int c) // push character back on input

{

    if(buf != 0)

        printf("ungetch: too many characnters\n");

    else

        buf = c;

}

Result: