s2_032.c

一般的C语言程序

#define PI 3.1415926
#define R1
main()
{ 
	float c,r,s;
	printf ("input a number: ");
	scanf("%f",&c);
	#if R
		r=PI*c*c;
		printf("area of round is: %f\\n",r);
	#else
		s=c*c;
		printf("area of square is: %f\\n",s);
	#endif
}