Transcript Mixing integer and f..

Mixing integer and floating point
numbers in an arithmetic operation
Previously discussed
• Java's automatic floating point conversion in arithmetic
expressions:
• All floating point values (float and double) in an
arithmetic operation (+, −, *, /) are converted to
double type before the arithmetic operation in
performed.
Previously discussed (cont.)
• Java's automatic integer conversion in arithmetic
operations:
• All integer values (byte, short and int) in an
arithmetic operations (+, −, *, /, %) are converted to
int type before the arithmetic operation in performed.
• However, if one of the values in an arithmetic
operation (+, −, *, /, %) is long, then all values are
converted to long type before the arithmetic operation
in performed.
Previously discussed (cont.)
• An very important (but rarely taught) fact about a
computer:
• A computer can only operate on data of the same
data type
Mixing integer and floating point numbers
in an arithmetic operation
• Java's automatic conversion in a mixed (integer and
floating point) arithmetic operation:
• All values in an mixed arithmetic operations (+, −,
*, /, %) are converted to double type before the
arithmetic operation in performed.
• Important note:
• The conversion rule is applied at the moment that
the arithmetic operation is performed
Mixing integer and floating point numbers
in an arithmetic operation (cont.)
• Example 1:
int a = 3;
double b = 4.5, c;
c = a + b;
// a (int) is converted to a double
// Then the addition is performed (on 2 doubles)
Mixing integer and floating point numbers
in an arithmetic operation (cont.)
• Example 2:
int a = 5, b = 2;
double c = 4.5, d;
d = c + a / b; // a/b is performed first.
// Because a and b are integers, the division
// a/b produces the quotient: a/b = 2 (not 2.5 !!!)
//
// Next we add: c + 2
// Because c is a double, the integer value 2
// is converted to double 2.0
// Result: 4.5 + 2.0 = 6.5
Exercise
• What is the type and the value printed by each of the print
statements in the following Java program:
public class Exercise2
{
public static void main(String[] args)
{
short a = 5;
int b = 2;
double c = 1.0;
double d = 5.0;
Exercise (cont.)
System.out.println( a / b / c );
System.out.println( a / c / b );
System.out.println( a / b );
System.out.println( d / b );
System.out.println( (a + 0) / b );
System.out.println( (d + 0) / b );
System.out.println( (a + 0.0) / b );
System.out.println( (d + 0.0) / b );
}
}
Exercise (cont.)
• Answers:
a / b / c = 2.0 (double)
a / c / b = 2.5 (double)
a/b
= 2 (int)
d/b
= 2.5 (double)
(a + 0) / b = 2 (int)
(d + 0) / b = 2.5 (double)
(a + 0.0) / b = 2.5 (double)
(d + 0.0) / b = 2.5 (double)
Exercise (cont.)
• Example Program: (Demo above code)
– Prog file:
http://mathcs.emory.edu/~cheung/Courses/170/Syllabus/04/Progs/
Exercise2.java
• How to run the program:
• Right click on link and save in a scratch directory
• To compile: javac Exercise2.java
• To run:
java Exercise2