While Loop Table

Question

I need to make a table of Celsius to Fahrenheit conversions. The output should be exactly like this:

-40.0C  is  -40.0F  -30.0C  is  -22.0F  -20.0C  is  -4.0F   -10.0C  is  14.0F   
-39.0C  is  -38.2F  -29.0C  is  -20.2F  -19.0C  is  -2.2F   -9.0C  is  15.8F    
-38.0C  is  -36.4F  -28.0C  is  -18.4F  -18.0C  is  -0.4F   -8.0C  is  17.6F    
-37.0C  is  -34.6F  -27.0C  is  -16.6F  -17.0C  is  1.4F    -7.0C  is  19.4F    
-36.0C  is  -32.8F  -26.0C  is  -14.8F  -16.0C  is  3.2F    -6.0C  is  21.2F    
-35.0C  is  -31.0F  -25.0C  is  -13.0F  -15.0C  is  5.0F    -5.0C  is  23.0F    
-34.0C  is  -29.2F  -24.0C  is  -11.2F  -14.0C  is  6.8F    -4.0C  is  24.8F    
-33.0C  is  -27.4F  -23.0C  is  -9.4F   -13.0C  is  8.6F    -3.0C  is  26.6F    
-32.0C  is  -25.6F  -22.0C  is  -7.6F   -12.0C  is  10.4F   -2.0C  is  28.4F    
-31.0C  is  -23.8F  -21.0C  is  -5.8F   -11.0C  is  12.2F   -1.0C  is  30.2F    

The trick is, you can only use one while loop for the whole thing. Also you can't just type everything as it is. I am strugling to figure out a way for how to start a new column each time it goes through the 10 conversions or something of that type, i made a program that works but its lame and kinda cheating:

public class TempConvWorking{

public static void main (String[] args){

    double celsius1 = -40.0, celsius2 = -30.0, celsius3 = -20.0, celsius4 = -10.0;
    double fahreheit1, fahreheit2, fahreheit3, fahreheit4;

    while (celsius4 < 0){

        fahreheit1 = (celsius1 * (1.8) + 32.0);
        fahreheit2 = (celsius2 * (1.8) + 32.0);
        fahreheit3 = (celsius3 * (1.8) + 32.0);
        fahreheit4 = (celsius4 * (1.8) + 32.0);
        System.out.printf ("%.1fC  is  %.1fF\t%.1fC  is  %.1fF\t%.1fC  is  %.1fF\t%.1fC  is  %.1fF\t\n",celsius1,fahreheit1,celsius2,fahreheit2,celsius3,fahreheit3,celsius4,fahreheit4);
        celsius1 += 1;
        celsius2 += 1;
        celsius3 += 1;
        celsius4 += 1;
    }
  }
}

so if anyone has suggestions please explain.

Answer 1

I strongly suggest you create a method doing the conversion from Celcius to Fahrenheit and in addition print it. In my example I will use conv(double celcius) which prints for example "40.0C is -40.0F".

There's a pattern: the ten lines i₀ until i₉ each contain the conversions for -40 + i, -30 + i, -20 + i and -10 + i.

Within the while loop, you must call the conv method four times.

int i = 0;
while (i < 10) {
    conv(-40 + i);
    conv(-30 + i);
    conv(-20 + i);
    conv(-10 + i);
    System.out.println();
    i++;
}

public static void conv(double celcius) {
    double fahrenheit = 1.8 * celsius + 32;
    System.out.printf("%.1fC  is  %.1fF\t" celcius, fahrenheit);
}

Answer 2

Well, they're ten degrees off from each other, so you can eliminate several variables to simplify the code somewhat:

public class TempConvWorking {
  public static void main (String[] args) {
    double celsius = -40.0;
    while (celsius < -30.0) {
      System.out.printf(
          "%.1fC  is  %.1fF\t%.1fC  is  %.1fF\t%.1fC  is  %.1fF\t%.1fC  is  %.1fF\t\n",
          celsius,
          1.8*celsius + 32.0,
          celsius + 10.0,
          1.8*celsius + 50.0,
          celsius + 20.0,
          1.8*celsius + 68.0,
          celsius + 30.0,
          1.8*celsius + 86.0);
      celsius++;
    }
  }
}

This code produces the specified output.

Answer 3

Assuming you want no counter variable outside the while loop and don't want to print more than one celsius-fahrenheit pair per iteration:

double celsius = -50.0;
double fahrenheit;

while (celsius < -1){

    if(celsius >= -10){
        celsius -= 39;
        System.out.println();
    }
    celsius1 += 10;
    fahreheit = (celsius * (1.8) + 32.0);
    System.out.printf ("%.1fC  is  %.1fF\t",celsius, fahrenheit);
}