/**
 * Convert US mpg to European liters / 100km
 * From the command line!!
 * @author gtowell
 * Created: Feb 2021
 * **/

#include <stdio.h>
#include <stdlib.h>  // needed for atof

#define GALLONS_PER_LITER   0.2641
#define KILOMETERS_PER_MILE 1.609

int main(int argc, char const *argv[])
{
    if (argc < 2) {
        printf("Usage: %s number\n", argv[0]);
        printf("       where: number is a US style MPG estimate\n");
        return 0;
    }
    double mpg = atof(argv[1]);
    double lp100km = (1 / mpg) * (1 / GALLONS_PER_LITER) * (1 / KILOMETERS_PER_MILE) * 100;
    printf("%5.2f liters per 100km \n", lp100km);
    return 0;
}