Homework & Coursework Questions

driver1.c:(.text+0x11): undefined reference to `write_message'
driver1.c:(.text+0x3c): undefined reference to `write_exp'
driver1.c:(.text+0x4b): undefined reference to `write_char'
driver1.c:(.text+0x68): undefined reference to `write_char'

/*      File:  display.h
        by:    Tep Dobry
        login: tep
        date:  20 Mar 03
*/

/*  This file contains the prototypes for useful funcitons in display.o
        library  */

#define MYFLUSH(c) while((((c) = getchar()) != '\n') && ((c) != 13));

void write_char(char);
/* This function is given a character and writes it to the display.
        The characters recognized to be written include the digits, '0'..'9',
        the operators, '+', '-', 'x', '/', and '=', the period, '.', and
        the special characters, 'q', ' ', '\n', and '\b'.  The
        special characters are explained in the documentation.
*/

void write_exp(char);
/* This function is given a character and writes it as an exponent to
        the dispaly.  The characters recognized to be written are
        the digits '0'..'9', and the minus sign, '-'.
*/

void write_message(char *);
/* This function is given a string which is written in the center
        of the top line of the display.  It also initializes the
        dispaly.
*/

void write_error(char *);
/* This function is given a string which is written to the bottom line
        of the display and causes the display to beep.
*/

void write_debug(int);
/* This function is given an integer which is written to the bottom line
        of the display to be used as debugging output in the program
*/

main()
{  char ch;

        /*  Initialize the dispaly with a message  */
        write_message("Display Test");

        /*  while not quitting  */
        while((ch = getchar()) != 'q')
        {
                /*  if exponent character */
                if( is_exp(ch))
                        /*  write the converted exponent character  */
                        write_exp(exp_value(ch));
                /*  otherwise write the character  */
                else write_char(ch);
        }

        /* write the q character to terminate the dispaly */
        write_char(ch);

}

void write_error(char *msg)
{
    fprintf(stderr, "Error msg: %s\n", msg);
}

char ch;