ABL electronic PIC Microcontrollers PIC16 - Manual (Page 99)

Type Qualifiers
Type qualifiers
const
and
volatile
are optional in declarations and do not actu-
ally affect the type of declared object.
Qualifier const
Qualifier
const
implies that the declared object will not change its value during
runtime. In declarations with
const
qualifier, you need to initialize all the objects
in the declaration.
Effectively, mikroC treats objects declared with
const
qualifier same as literals or
preprocessor constants. Compiler will report an error if trying to change an object
declared with
const
qualifier.
For example:
const double PI = 3.14159;
Qualifier volatile
Qualifier
volatile
implies that variable may change its value during runtime
indepent from the program. Use the
volatile
modifier to indicate that a variable
can be changed by a background routine, an interrupt routine, or an I/O port.
Declaring an object to be volatile warns the compiler not to make assumptions
concerning the value of the object while evaluating expressions in which it occurs
because the value could change at any moment.
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