Question about the C language: what is a macro?

http://gcc.gnu.org/onlinedocs/cpp/Macros.html[^]
http://stackoverflow.com/questions/1358232/why-use-macros-in-c[^]

A macro is something the C compiler not even sees.

According to the first entry in a quick-Google-search (Macros - The C Preprocessor[^]):



That is:

• macros are C preprocessor stuff.
• Using Google you may find a lot of documentation about.

In any case here you are a simple (silly, there are spectacular - and cryptic - usages of macros) example:

#define BUFSIZE  100
//...
int buf[BUFSIZE];
//...
if (k>BUFSIZE)
{
  //...
}

the preprocessor replaces every occurrence of the macro BUFSIZE with the number 100, thus the C compiler parses (something like) the following source:

//...
int buf[100];
//...
if (k>100)
{
  //...
}