What is macros in C

A macro is a fragment of code that took its name. When we use the name of the macro-program, which replaces the contents of the macro. You can specify any valid identifier as a macro, even if AC is the key word. There are two types of macros. One is a macro-like object, and the second is a function-like macro. Macro-object as the parameters of the function-like macros do not. The general syntax to declare a symbol as a macro for each of:

For object-like macros:

 #define <identifier> <replacement token list>

For example:

#include<stdio.h>

#include<conio.h>

#define sum a+b

void main()

{

Clrscr();

int a=5,b=10,c;

c=sum; //if we give the semicolon (;)when we define the macro; then we cannot give the semicolon when we write the name of identifier. If we give the semicolon when we define the macro, then we give the semicolon when we write the name of identifier in program

printf(“The sum of a+b is: %d”,c);

getch();}

For function-like macros:

#define <identifier> (<parameter list>) <replacement token list>

For example:   

#include<stdio.h>

#include<conio.h>

#define square(x) x*x;

Void main()

{

Clrscr();

int i=2,j;

j=square(i) //Here is no semicolon because I give the semicolon when I define the macros.

printf(“The value of j is: %d”,j);

getch();
}

 The #undef directive removes the definition of a macro.

Written by arnob;