Data types:

There are 8 primitive data types and many other variable types created in classes.

integers:

• exact
• no overflow (need extra checking; there may be built in functions to check this)
• divide by zero --> exception (crash)
• Default type is "int". To specify a long: 52L

floating:

• rounding errors are possible
• overflow error???
• divide by zero --> infinity
• divide zero by zero --> NaN (not a number)
• default type is "double". To specify a float: 5.2f or 5.2F . A double could be written as 19.4D
• enter numbers as 11.0 not 11
• Apparently there is also a way to get +0 and -0 as numbers.

Strange stuff: if x is NotaNumber and y = x; y==x is still false. One NaN is never equal to another NaN!

Type in and run this program: DoubleMath.java

Entering other base numbers:

• int n = 055; <--- octal (scary! easy mistake)
• int n= 0xFF; <--- hexadecimal

Casting:

int i = 5;
int j = 2;
double result;

result = i / j; //integer division; result=2
result = (double) i / (double) j //real division; result=2.5

Java will implicity cast operants in a mixed expression to match the precision of the variable storing the result.

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