/*********************
 * Name: Geoff Towell
 * Purpose: Convert Celcius to Fahrenheit
 *          Doing it manually to preven scanf loop
 * Wrttten: August 5, 2019
 * Modified: Sep 6, 2019
 *           Sep 12 and 17, 2019
 *********************/

#include <stdio.h>
#include<stdlib.h>
#include "c2fsafe2.h"

#define FREEZING 32.0
#define SCALE 1.8
#define CC(v) (FREEZING + SCALE*v)

/**
 * Read one complete line of text and extract an integer from that line
 * ie everything to the \n from the keyboard.
 * so '123' is translated into the integer 123.
 * Stop accumulating into the integer on the first non-digit.
 * That is '123abd123' would yeild 123  
 * Also the integer must start the line.  So 'a123' whould return 0.
 * Known limitations: this function does not handle negative numbers
 *                    does not handle integers larger than max-int
 **/

int main(void)
{
    double f;
    int c;
    while (1)
    {
	printf("Enter a Celcius temperature: ");
	c = myatoi();
	if (c<-273.15) 
	{
	    printf("The number you entered %d is below absolute zero\nSo it has not been converted to Fahrenheit\n", c);
	}
	else
        {
	    f = CC(c);
	    printf("Celcius: %d  Fahrenheit: %.1f\n", c, f);
	}
    }
    return 0;
}

int myatoi()
{
    int keepAdding=1;
    int result = 0;
    char inChar;
    while ('\n' != (inChar=getchar()))
    {
	if (keepAdding && '0'<=inChar && '9'>=inChar)
	{
	    result = result*10 + (inChar-'0');
	}
	else
	{
	    keepAdding=0;
	}
    }    
    return result;
}