question3.java

java课程的资料以及实验的代码

class ComputeArea
{
	 
	public static void main(String args[])
	{
		final float PI=3.14159265f; //definition of constant PI
		int length=args.length;
		if (length<1)
		{
			System.out.println("invalid number of arguments\n");
			System.exit(1);
		};
		float radius=Float.parseFloat(args[0]); //obtain radius
		if (radius<0)
		{
			System.out.println("invalid arguments\n");
			System.exit(1);
		};
		float perimeter=2*PI*radius; //compute perimeter
		float area=PI*radius*radius; //compute area
		System.out.println("Perimeter="+perimeter+" area="+area);
	}
}