Remote-processing CAMBASIC Manuel d'utilisateur télécharger pdf (Page 16)

Concepts - 10

> greater than X> Y

< less than X< Y

>= greater than X> = Y

or equal to

<= less than X< = Y

or equal to

Relational operations return a value of “0” if false, – “1” if true.

Logical Operators

Logical operators perform logical, or Boolean operations on numeric values. Just as relational operators usually make

decisions regarding program flow, logical operators usually connect two or mor e relations and return a true or false value

to be used in a decision (see “IF statement” in CAMBASIC COM MAN DS).

A logical operator takes a combination of true– false values and returns a true or false result. An operand of a logical

operator is considered “ true” if it is not equal to zer o (like the – 1 retur ned by a r elational oper ator), or “ false” if it is

equal to zero. T he result of the logical oper ation is a num ber which is, again, “tr ue” if it is not equal to zero, or “ false” if

it is equal to zero. T he number is calcu lated by per forming the operation, bit by bit.

The logical operators are NOT, AND, XOR and OR. In the following table. (“ T” indicates a true, or nonzero value.

“F” indicates a false, or zero value.). The operators are listed in order of precedence.

A NOT A A B A AND B

T F T T T

F T T F F

F T F T F

F F F F F

A B A OR B A B A XOR B

T T T T T F

T F T T F T

F T T F T T

F F F F F F

Logical operations are carried out on 16– bit operands with 16– bit results. The examples use 8– bit operands for

simplicity.

The OR operator essentially detects the presence of a binary “ 1” in either operand. For example:

Operand 1 0001 0111 = 23

Operand 2 0100 1010 = 74

Operand 1 0101 1111 = 95

OR Operand 2

The AND operator detects the coincidence of two binary “ 1”s.

Operand 1 0001 0111 = 23

Operand 2 0100 1010 = 74

Operand 1 0000 0010 = 2

1 2 ... 11 12 13 14 15 16 17 18 19 20 21 ... 207 208

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Remote-processing CAMBASIC Manuel d'utilisateur Page 16