Mixing integer and floating point numbers in an

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 Exercise 2 { 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/ Exercise 2. java • How to run the program: • Right click on link and save in a scratch directory • To compile: javac Exercise 2. java • To run: java Exercise 2