Write an alternate getline to read an entire input line:this makes getch and ungetch unnecessary.Revise the calculator to use this approach.

#include <stdio.h>
#include <ctype.h>

#define   MAXLINE   100
#define   NUMBER   '0'  /* signal that a number was found */

int getline(char line[], int limit);

int li = 0;   /*input line index */
char line[MAXLINE];    /* one input line */

/* getop: get next operator or numeric operand    */
int getop(char s[]){
    int c, i;

    if(line[li] =='\0')
        if(getline(line, MAXLINE) == 0)
             return EOF;
        else
            li = 0;
    while ((s[0] = c = line[li++]) == ' ' || c == '\t')
              ;
    s[i] = '\0';
    if (!isdigit(c) && c != '.')
         return c;     /* not a number */
    i = 0;
   if (isdigit(c))     /* collect  integer part */
       while(isdigit(s[++i] = c =line[li++]))
          ;
   if(c == '.')   /* collect fraction part */
       while(isdigit(s[++i) =c =line[i++]))
           ;
   s[i] = '\0';
   li--;
   return NUMBER;
}