/* ECP: FILEname=fig4_19.c */
/* 1*/   #include <stdio.h>

/* 2*/   #define Pi 3.1416
/* 3*/   #define Circle 1
/* 4*/   #define Rectangle 2
/* 5*/   #define Square 3

/* 6*/   #define NoArea ( -1.0 )

/* 7*/   double
/* 8*/   ProcessCircle( void )
/* 9*/   {
/*10*/       double Dim1;

/*11*/       printf( "Enter radius: " );
/*12*/       if( scanf( "%lf", &Dim1 ) != 1 )
/*13*/           return NoArea;
/*14*/       printf( "Shape is circle radius %.2f; ", Dim1 );
/*15*/       return Dim1 * Dim1 * Pi;
/*16*/   }