Sunday, May 13, 2012

Diiference between MACRO and CONST ?

Diiference between MACRO and CONST ?

MACRO
1.It is a replaces the test with a value
2.It value can't be altered but it is changed using pre-
processor derivative  #undef  .
3.once it is defined it is can't be localized like  normal value
(same name can't used inside like local)
4.It is preprocessor directive it process all the value before it compile

CONST
1.it stored in ROM. we can using to other files of C using extern
 that is not possible in MACRO.
2. It have address so we can use pointer as well as size of operator
3.It can be localized  in side a function
4. it is optimized by compiler

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