For many situations, the int data type will be adequate for storing integer variables. It can hold values between (roughly) + or - 2 billion. You can multiply two integers as follows:
UBUNTU > cat prog7.java
public class prog7
{
public static void main (String args[])
{
// Declare 2 integers:
int num1 = 1234;
int num2 = 4321;
// Multiply them together:
int num3 = num1 * num2;
// Display the result:
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num1 * num2 = " + num3);
}
}
UBUNTU > javac prog7.java
UBUNTU > java prog7
num1 = 1234
num2 = 4321
num1 * num2 = 5332114
UBUNTU >
... but what happens if the result is too big to store in an int variable?
UBUNTU > cat prog8.java
public class prog8
{
public static void main (String args[])
{
// Declare 2 integers:
int num1 = 123456;
int num2 = 654321;
// Multiply them together:
int num3 = num1 * num2;
// Display the result:
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num1 * num2 = " + num3);
}
}
UBUNTU > javac prog8.java
UBUNTU > java prog8
num1 = 123456
num2 = 654321
num1 * num2 = -824525248
UBUNTU >
public class prog8
{
public static void main (String args[])
{
// Declare 2 integers:
int num1 = 123456;
int num2 = 654321;
// Multiply them together:
int num3 = num1 * num2;
// Display the result:
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num1 * num2 = " + num3);
}
}
UBUNTU > javac prog8.java
UBUNTU > java prog8
num1 = 123456
num2 = 654321
num1 * num2 = -824525248
UBUNTU >
According to my calculator, the result should be 80,779,853,376 so some arithmetic overflow must have taken place. As soon as I find out how to handle this, I will do a worked example to demonstrate.
If you have a Java book on Amazon, which you would like to advertise here for free, please write to me at international_dba@yahoo.co.uk.
