ex01-02.c

里面包含很多c语言的源码

#include <stdio.h>

int radius, area;

int main( void )
{
   printf( "Enter radius (i.e. 10): " );
   scanf( "%d", &radius );
   area = (int) (3.14159 * radius * radius);
   printf( "\n\nArea = %d\n", area );
   return 0;
}