Java programming course: 5.11 Arithmetic operations on primitives

In the previous lesson you learnt about casting.

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Arithmetic operations on primitives

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The arithmetic operators are:

• + for addition: e.g., a + b
• - for subtraction: e.g., a - b
• * for multiplication: e.g., a * b
• / for division: e.g., a / b
• % for modulus (i.e., the remainder after division) : e.g., a % b
• ++ for increment by 1: e.g., a++ or ++a
• -- for decrement by 1: e.g., a-- or --a

Take careful note of how the following calculations are performed:

// Division
double d = 3.0 / 4.0;	// d becomes 0.75
int i = 3 / 4;		// i becomes 0 (int has no decimals)
int j = 15 / 2; 		// j becomes 7

// if either value is floating point, the result will be as well
double e = 15 / 2.0;	// e becomes 7.5

// here both operands are int so that is computed first
double f = 15 / 2;		// f becomes 7.0

// modulus (remainder after division)
int k = 34 % 5;		// k becomes 4
double g = 3.5 % 2.1;	// f becomes 1.4

// negation
int a = 2;
int b = -a;		// b becomes -2 (- is prefix op rather than
                                                   subtraction here)

// precedence rules – use brackets to avoid ambiguity
int p = 3 + (4 * 5);	// p becomes 23
int q = (3 + 4) * 5;	// q becomes 35

// increment & decrement (++, --)
int r = 10;
int s = r++;		// r becomes 11, but s becomes 10...!!!

r = 10;
s = ++r;           // now both r and s will be 11
 

In the next section of lessons you will learn about arrays, loops, and sorts.

Next lesson 6.1 Arrays, loops, and sorts