7.23 compilation preprocessing DAY14

---note---

Pre-processing//prior to compilation

#define PI 3.14

1. Macro definition: #define

2. File contains: #include

3. Conditional compilation: #if #end If

Generally uppercase

Macro definition does not check for errors

No replacement when "" is present

Do not allocate memory space

#define S (A, b) a*b

Area = S (3,2)

Area = 6

An # include contains only a single file

F1 contains static in F2,f2 (static is also valid in F1)

---note---

#include <stdio.h>
#define ADD (x) x+x
int main ()
{
int m=1,n=2,k=3;
int Sum=add (m+n) *k;
printf ("sum=%d", sum);
return 0;
}

7.23 compilation preprocessing DAY14