Mikroelektronika MIKROE-738 Datenbogen

242

mikoC PRO for PIC32

MikroElektronika

Operands of logical operations are considered true or false, that is non-zero or zero. Logical operators always return 1 

or 0. Operands in a logical expression must be of scalar type.

Logical operators 

&&

 and

 ||

 associate from left to right. Logical negation operator ! associates from right to left.

Logical Operators Overview

||

0

1

1

1

&&

logical AND

5

||

logical OR

4

!

logical negation

14

&&

0

0

0

1

Logical Operations

!

1

0

Precedence of logical, relational, and arithmetic operators was designated in such a way to allow complex expressions 

without parentheses to have an expected meaning:

c >= ‘0’ && c <= ‘9’;    /* reads as: (c >= ‘0’) && (c <= ‘9’) */

a + 1 == b || ! f(x);    /* reads as: ((a + 1) == b) || (! (f(x))) */

Logical AND 

&&

 returns 1 only if both expressions evaluate to be nonzero, otherwise returns 0. If the first expression 

evaluates to false, the second expression will not be evaluated. For example:

a > b && c < d;     /* reads as  (a > b) && (c < d) */

Logical OR 

||

 returns 1 if either of expression evaluates to be nonzero, otherwise returns 0. If the first expression 

evaluates to true, the second expression is not evaluated. For example:

a && b || c && d;  /* reads as: (a && b) || (c && d) */

Logical Expressions and Side Effects

General rule regarding complex logical expressions is that the evaluation of consecutive logical operands stops at the 

very moment the final result is known. For example, if we have an expression 

a && b && c

 where 

a

 is false (0), then 

operands 

b

 and 

c

 will not be evaluated. This is very important if 

b

 and 

c

 are expressions, as their possible side effects 

will not take place!