define in C
In the C Language, the #define directive allows the definition of macros within your source code.
Macro definitions are not variables and cannot be changed by your program code like variables.
#include <stdio.h>
#define PI 3.14159
int main ()
//pi = 3.1416
{
float area, r;
scanf("%f", &r);
area = PI * (r * r);
printf("area is %f", area);
return 0;
}
//enter 3
Output
area is 28.274309
