3.5第二次上机作业

1.定义圆的半径,求圆的面积

package work;

public class Pra1 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int r=2;
        System.out.println(3.14*r*r);
    }

}

2.华氏度摄氏度转换

package work;

public class Copy_2_of_Pra1 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
         double d=41;
         System.out.println((d-32)*5/9);
         double s=5;
         System.out.println(s*9/5+32);
         
    }

}

3.a  b 变量值的互换

package work;

public class Copy_3_of_Pra1 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a = 100,b = 102;
        int temp = a;
        a = b;
        b = temp;
         System.out.println(a+" "+b);
    }

}

4.任意五位数,保留到百位

package work;

public class CopyOfPra1 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a =12345;
        int b;
        b=a/100*100;
        
        System.out.println(b);
    }

}

5.0~1000的整数,求各位数的和

package work;

public class Copy_4_of_Pra1 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a = 234;
        int b, c, d, sum;
        
        b = a / 100 ;
        c = a  / 10 % 10;
        d = a % 10;
        sum = b +c +d ;
        System.out.println("结果为" + sum);
    }

}

6.字母大小写转换

package work;

public class Copy_5_of_Pra1 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for(char a='A';a<='Z';a++)
            System.out.println((int) a);
        for(char b='a';b<='z';b++)
            System.out.println((int) b);
    
    }

}