Exercise 4.10. An alternate organization uses getline to read an entire input line

Exercise 4.10. An alternate organization uses getline to read an entire input line; this makes getch and ungetch unnecessary. Revise the calculator to use this approach.

/* getop: get next character of numeric operand */

int getop(char s[])

{

    int c, i;

    if(line[m] == '\0')

    {

        if(getlin(line, MAXLINE) == 0)

            return EOF;

        else

            m = 0;

    }

    while((s[0] = c = line[m++]) == ' ' || c == '\t')

        ;

    s[1] = '\0';

    i = 0;

    if(!isdigit(c) && c != '.') // not a number

        return c;

    i = 0;

    if(isdigit(c)) // collect integer part

        while(isdigit(s[++i] = c = line[m++]))

            ;

    if(c == '.') // collect fraction part

        while(isdigit(s[++i] = c = line[m++]))

            ;

    s[i] = '\0';

    m--;

    return NUMBER;

}