Area=28.27
Syntactic Sugar
Syntactic sugar is the alteration of programming syntax according to the will of programmer. For example:
#define LT <
Every time the program encounters LT, it will be replaced by <.
Second form of preprocessing directive with #define is:
Macros with argument
Preprocessing directive #define can be used to write macro definitions with parameters as well in the form below:
#define identifier(identifier 1,.....identifier n) token_string
Again, the token string is optional but, are used in almost every case. Let us consider an example of macro definition with argument.
#define area(r) (3.1415*r*r)
Here, the argument passed is r. Every time the program encounters area(argument), it will be replace
by(3.1415*argument*argument). Suppose, we passed (r1+5) as argument then, it expands as below:
area(r1+5) expands to (3.1415*(r1+5)(r1+5))
C Program to find area of a circle, passing arguments to macros. [Area of circle=πr2]
#include <stdio.h>
#define PI 3.1415
#define area(r) (PI*r*r)
int main(){
int radius;
float area;
printf("Enter the radius: ");
scanf("%d",&radius);
area=area(radius);
printf("Area=%.2f",area);
return 0;
}
Predefined Macros in C language