Mikroelektronika MIKROE-738 Datenbogen

mikroC PRO for PIC32

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Logical vs. Bitwise

Be aware of the principle difference between how bitwise and logical operators work. For example:

0222222 &  0555555     /* equals 000000 */

0222222 && 0555555     /* equals 1 */

~ 0x1234               /* equals 0xEDCB */

! 0x1234               /* equals 0 */

The conditional operator 

? :

 is the only ternary operator in C. Syntax of the conditional operator is:

The 

 is evaluated first. If its value is true, then 

 evaluates and 

 is ignored. 

If 

 evaluates to false, then 

 evaluates and 

 is ignored. The result will be a 

value of either 

 or

 expression3

 depending upon which of them evaluates.

Conditional operator associates from right to left.

Note: The fact that only one of these two expressions evaluates is very important if they are expected to produce side effects! 

Here are a couple of practical examples:

max = ( a > b ) ? a : b;

c = ( c >= ‘a’ && c <= ‘z’ ) ? ( c - 32 ) : c;

Conditional Operator Rules

 must be a scalar expression; 

 and 

 must obey one of the following rules:

 

1. Both expressions have to be of arithmetic type. 

 and 

 are subject to usual  

 

    arithmetic conversions, which determines the resulting type. 

 

2. Both expressions have to be of compatible 

struct

 or 

union

 types. The resulting type is a structure or  

 

    union type of 

 and 

. 

 

3. Both expressions have to be of 

void

 type. The resulting type is 

void

. 

 

4. Both expressions have to be of type pointer to qualified or unqualified versions of compatible types.  

 

    The resulting type is a pointer to a type qualified with all type qualifiers of the types pointed to by both  

 

    expressions. 

 

5. One expression is a pointer, and the other is a null pointer constant. The resulting type is a pointer to a  

 

    type qualified with all type qualifiers of the types pointed to by both expressions.

 

6. One expression is a pointer to an object or incomplete type, and the other is a pointer to a qualified or  

 

    unqualified version of 

void

. The resulting type is that of the non-pointer-to-

void

 expression.