Thread: pushback question (reverse polish calculator)

Originally Posted by Tool

You mean deleting the if(c!= EOF).

Yep!

Originally Posted by Tool

But then ill have to edit getch().

If you use the source given in the "Bible", array buf[MAXBUF] is of type char but you have it of type int, and that's all that's needed. But testing for EOF in ungetch() doesn't make any sense when EOF isn't even being pushed back.

Originally Posted by Tool

I was thinking about something like this:

Code:

#include "calc.h"

int buf = EOF;

int getch()
{
    int temp;
    
    if(buf == 1) return EOF;
    if(buf == EOF)
    {
      temp = getchar();
    }
    else
    {
      temp = buf;
      buf = EOF;
    }
    
    return temp;
}

void ungetch(int c) //stores the temp char
{
     if(c == EOF)
     {
       buf = 1;
       return;
     }
     
     buf = c;
}

This will work only if you're actually pushing back an EOF, but are you?