macro substitution

macro

Macro substitution is an identifier that is defined with predefine value. In the given program pre-define value work as a substituted value for identifier and when we call(write) identifier in the program its value will be substituted with a pre-define value which is called a macro substitution. it is done with # define value. 

syntax  

# define identifier ( value )   

 

it has many ways to write a program some of them are here  

a. simple macro substitution  

 b. argument macro substitution  

c. nested macro substitution  

 

 a. simple macro substitution 

Let's be clear from here,  

 we use the # define 10 functions to define a macro and where ever we use VALUE in the program 10 will be replaced with VALUE. To define a macro we use capital alphabets and we don't need to apply semi-colon(;). They are also used to define symbolic constants and to identify them we use capital alphabets. in macro substitution we can use expression too, we have to use a ( ) bracket to get the correct output. To be more clear let's have a look at the example given below. 

Simple macro example 

 int d = VALUE - 5; 

 d = 5:  // it works as 10-5 = 5 

  

use of expression example   

 #define AREA (4+1) 

 #define REAA (5-2) 

 int x = AREA * REEA 

/*   

It will follow the operators precedence process to execute. 

x = (4+1) * (5-2); 

 x = 5*3; 

 x = 12; 

*/ 

Output  

12  

 program 

#include <stdio.h>

#include <conio.h>

#define ALL 10000

#define PROGRAMMING "all programing solution"

void main()

{

    int a = 1000;

    if (ALL > a) // the condition is true

    {

        printf(PROGRAMMING); // it will print "all programming solution" as 

an output because it Is defined in the PROGRAMMING.

    }

    getch();

}

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