Thread: Please Help: Random Dice Roll:

Hello,

I am a absolute beginner. I am trying to create a program that will randomly roll a die 600 times and display a table with the frequency and percent of each face number. Please help me understand what I need to do to make the following code work:


public class diceroll
{

/**
*
*/
public static void main(String[] args)
{
int toRoll = 600, x,i=0, c1 = 0, c2 = 0, c3 = 0, c4 = 0, c5 = 0,
c6 = 0;
double pct1, pct2, pct3, pct4, pct5, pct6;

for (i=0;i<=toRoll; i++)
{
x = (int)(Math.random()*6)+1;
if (x==1)
c1++;
else if (x==2)
c2++;
else if (x==3)
c3++;
else if (x==4)
c4++;
else if (x==5)
c5++;
else if (x==6)
c6++;
}
pct1 = (c1 * 100.0) / (double)toRoll;
pct2 = (c2 * 100.0) / (double)toRoll;
pct3 = (c3 * 100.0) / (double)toRoll;
pct4 = (c4 * 100.0) / (double)toRoll;
pct5 = (c5 * 100.0) / (double)toRoll;
pct6 = (c6 * 100.0) / (double)toRoll;

System.out.printf("Face\tFrequency\t%\n");
System.out.printf("-------------------\n");
System.out.printf("1\t%d\t%10.1f\n", c1);
System.out.printf("2\t%d\t%10.1f\n", c2);
System.out.printf("3\t%d\t%10.1f\n", c3);
System.out.printf("4\t%d\t%10.1f\n", c4);
System.out.printf("5\t%d\t%10.1f\n", c5);
System.out.printf("6\t%d\t%10.1f\n", c6);

}
}

Originally Posted by dbs360

        System.out.printf("Face\tFrequency\t%\n");

Since '%' is a format specifier, you have to do something special to print a '%' sign.

Personally, I would spell out "percent" but if you want to print a percent sign, use "%%" in the format String.

Originally Posted by dbs360

        System.out.printf("1\t%d\t%10.1f\n", c1, pct1);

After you fix the first error, what error message do you get when it gets to this line?


Cheers!

Z

I get an error when I use the printf to output things...it is:

Exception in thread "main" java.util.UnknownFormatConversionException: Conversion = '
'
	at java.util.Formatter.checkText(Unknown Source)
	at java.util.Formatter.parse(Unknown Source)
	at java.util.Formatter.format(Unknown Source)
	at java.io.PrintStream.format(Unknown Source)
	at java.io.PrintStream.printf(Unknown Source)
	at diceRollExample.diceRollExample.main(diceRollExample.java:41)

The same applies if I try to format the output of each dice roll.

Thanks guys. I figured out my problem just by editing my code. My problem was the first printf line. I didnt assign the f inside the () as I did in the following output lines, so I just simply had to change the first one to println in that format. So the working code for this is as follows. Thanks again for your help



public class diceroll
{

/**
*
*/
public static void main(String[] args)
{
int toRoll = 600, x,i=0, c1 = 0, c2 = 0, c3 = 0, c4 = 0, c5 = 0,
c6 = 0, sum1;
double pct1, pct2, pct3, pct4, pct5, pct6, sum2;

for (i=0;i<toRoll; i++)
{
x = (int)(Math.random()*6)+1;
if (x==1)
c1++;
else if (x==2)
c2++;
else if (x==3)
c3++;
else if (x==4)
c4++;
else if (x==5)
c5++;
else if (x==6)
c6++;
}
pct1 = (c1 * 100.0) / (double)toRoll;
pct2 = (c2 * 100.0) / (double)toRoll;
pct3 = (c3 * 100.0) / (double)toRoll;
pct4 = (c4 * 100.0) / (double)toRoll;
pct5 = (c5 * 100.0) / (double)toRoll;
pct6 = (c6 * 100.0) / (double)toRoll;

sum1= c1+c2+c3+c4+c5+c6;
sum2= pct1+pct2+pct3+pct4+pct5+pct6;

System.out.println("Face\tFrequency\t%");
System.out.printf("---------------------------\n");
System.out.printf("1\t%d\t%10.1f\n", c1, pct1);
System.out.printf("2\t%d\t%10.1f\n", c2, pct2);
System.out.printf("3\t%d\t%10.1f\n", c3, pct3);
System.out.printf("4\t%d\t%10.1f\n", c4, pct4);
System.out.printf("5\t%d\t%10.1f\n", c5, pct5);
System.out.printf("6\t%d\t%10.1f\n", c6, pct6);
System.out.printf("---------------------------\n");
System.out.printf("Total:\t%d\t%10.1f\n", sum1, sum2);
}
}