Arithmetic and Boolean Operations

Tom Kelliher, CS 116

Oct. 18, 2000

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Assignment

Nothing new. Should have read up to 5.4.

From Last Time

Scope and access.

Outline

1. Arithmetic operators.

2. Logical operators.

3. Return exam.

Coming Up

Logical operations, assignments, statements.

Arithmetic Operators

Suppose we know the following:

int i = 5;
int j = -3;
int k = 12;

k - i * 2

i - 4 - j

4 / i * 5

i - 2 * k + j

How can we change the order of evaluation?

Arithmetic Operators

1. Binary operators: +, -, *, /, %.
   • Precedence?

   • Associativity?

   • Type matters.

   • No mixed-type operations.

     Implicit type conversion. ``Smaller'' to ``larger'' types.

   • Explicit type conversion with casts. Must be used when converting larger to smaller types.

     Casts are unary operators.

     Example: generating a random integer from 1 to 10 (inclusive).

     Math.random() generates a random double such that . How can we use it to solve this problem?

2. Unary operators: -, ++, -- (and casts).

   Use increment and decrement judiciously.

   Unary arithmetic operators have higher precedence than binary.

   Associativity?

Math Class Methods

abs(), ceil(), floor.

Logical Operators

Comparison and boolean operators.

Arithmetic Comparison Operators

<, <=, ==, !=, >, >=.

1. Lower precedence than binary arithmetic operators.

   Equality, inequality one level below others.

2. Associate left-to-right.

3. Take numeric arguments. Return a boolean.

   Why is 0.0 < x < 1.0 illegal?

Examples. Assume:

int    n = 3;
double x = 4.8;

n < 3

n <= 3

n < x

(n + 3) == 2

2 * n != x - 1.0

n >= n

n / 4 > 0

n >= n == n < 3

Logical Operators

1. Take boolean argument(s). Return a boolean value.

2. Binary: &&, ||.

   Lower precedence than equality, inequality.

   Associate?

3. Unary: !.

   Unary precedence.

   Associate?

4. Deriving the truth tables.