C :

#include<stdio.h>
#include<math.h>
const double Pi = 3.14;
double Area( double Redius )
{
	double Are;
	Are = Pi * pow( Redius, 2 );
	return Are;
}
double Circumference( double Redius )
{
	double Cir;
	Cir = 2 * Pi * Redius;
	return Cir;
}
int main( int argc, char **argv )
{
	double Redius;
	scanf( "%lf", &Redius );
	double Are,Cir;
	Are = Area( Redius ), Cir = Circumference( Redius );
	printf( "周长=%.2f\n面积=%.2f\n", Cir, Are );
	return 0;
}

C++ :

//计算周长面积 
#include <iostream>
using namespace std;

int main ()
{
  float r, c, s;
  cin>>r;

  c = 3.14*r*2;
  s = 3.14*r*r;


  // 打印结果 
  cout <<"周长="<<c<<endl;
  cout <<"面积="<<s<<endl;
  // 结束程序 
  return 0;
}

Java :

import java.math.BigDecimal;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		double r=sc.nextDouble();
		double c=2*3.14*r;
		double area=3.14*Math.pow(r, 2);
		BigDecimal bg1=new BigDecimal(c);
		BigDecimal bg2=new BigDecimal(area);
		System.out.println("周长="+bg1.setScale(2, BigDecimal.ROUND_HALF_UP));
		System.out.println("面积="+bg2.setScale(2, BigDecimal.ROUND_HALF_UP));
	}
}