What is a macro in C? how to use macro?

A macro is a preprocessor directive that provides a mechanism for token replacement in your source code. Macros are created by using the #define statement.


example of a macro:

Macros can also utilize special operators such as the stringizing operator (#) and the concatenation operator (##).The stringizing operator can be used to convert macro parameters to quoted strings, as in the following example:

#define DEBUG_VALUE(v) printf(#v ? is equal to %d.n?, v)

In your program, you can check the value of a variable by invoking the DEBUG_VALUE macro:

...
int x = 20;
DEBUG_VALUE(x);
...

The preceding code prints ?x is equal to 20.? on-screen. This example shows that the stringizing operator used with macros can be a very handy debugging tool.

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More Useful Topics...

 

History Of C..

In the beginning was Charles Babbage and his Analytical Engine, a machine
he built in 1822 that could be programmed to carry out different computations.
Move forward more than 100 years, where the U.S. government in
1942 used concepts from Babbage’s engine to create the ENIAC, the first
modern computer.
Meanwhile, over at the AT&T Bell Labs, in 1972 Dennis Ritchie was working
with two languages: B (for Bell) and BCPL (Basic Combined Programming
Language). Inspired by Pascal, Mr. Ritchie developed the C programming
language.

My 1st Program...


#include
#include
void main ()
{
clrscr ();
printf ("\n\n\n\n");
printf ("\t\t\t*******Pankaj *******\n");
printf ("\t\t\t********************************\n");
printf ("\t\t\t\"Life is Good...\"\n");
printf ("\t\t\t********************************");
getch ();
}

Next Step...


#include
#include

void main ()
{
clrscr ();
printf ("\n\n\n\n\n\n\n\n");
printf ("\t\t\t --------------------------- \n\n");

printf ("\t\t\t | IGCT, Info Computers, INDIA | \n\n");
printf ("\t\t\t --------------------------- ");

getch ();

}

Hits!!!