MACRO

MACRO

 Macro is a Pre-processor directive which is used to declare symbolic constants.

Example:  # define UPPER 25

The  above statement is called ‘Micro Defination’(Macro), ‘UPPER’ is called ‘ MACRO TEMPLATE’

And 25 is called corresponding ‘macro expansion’.

It is customary to use capital letters for micro template.

Macro   definition never to be terminated   by a semicolon.

Macro can have arguments.

  Example:

                # define AREA(x)  (3.14 *X *X)

                         Main()

                        {

                         Float r1=6.25,a;

                         a=AREA(r1);

                         printf(“Area is =%f”,a);

                           }

MACROS Vs Function

In a micro call preprocessor replaces the micro template  with  it’s micro expansion.

In a  function call, the control is passed to  function along with  certain arguments, after performing the  talks in that fun a useful value is returned back.

Macros make the program  run faster but increase the  program size.

 Function make the program smaller and  compact  but takes time to passing the control between  functions.

File Inclusion

   This directive causes one file to be included in another file. There are two ways to write

    # include<filename.h>

    # include “filename.h”

1.  Macro Expansion.