java实验作业1

//1已知圆的半径为10,求其周长及面积
package calsswork3;

public class test3_1 {
  //求周长
    public static double C(int r) {
      return 2*r*Math.PI;
    }
    //求面积
    public static double S(int r) {
      return r*r*Math.PI;
    }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
        int r=10;
        System.out.println("圆的周长是:"+C(r));
        System.out.println("圆的面积是:"+S(r));
  }

}
//2根据自由落体公式s=v0t+gt*2/2,求解s,其中v0=4m/s,g=9.8,t=0.5
package calsswork3;

public class test3_2 {
    //位移公式
    public static double s(int v,double g, double t) {
      return v*t+g*t*t/2;
    }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
      int v=4;
      double g=9.8;
      double t=0.5;
      System.out.println("s="+s(v,g,t));
  }

}
//3输入一个整数判断其奇偶性
package calsswork3;

import java.util.Scanner;

public class test3_3 {
    //判断函数
  public static void pd(int x) {
    if(x%2==0) {
      System.out.println(x+"是偶数");
    }
    else {
      System.out.println(x+"是奇数");
    }
  }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
      System.out.println("请输入一个整数:");
      Scanner in=new Scanner(System.in);
      int x=in.nextInt();
      pd(x);
  }

}
//4输入三角形的三边长a,b,c判断是否构成三角形.
//如果是三角形,计算出三角形的面积
package calsswork3;
import java.util.Scanner;
public class test3_4 {

    //判断三边能否构成三角形
  public static int panduan(double a,double b,double c) {
       int f;
      if(a>0&&b>0&&c>0&&(a-b)<c&&(a+b)>c&&(a-c)<b&&(a+c)>b&&(b-c)<a&&(b+c)>a) {
        f=1;
      }
      else {
        f=0;
      }
      return f;
        
    }
    //计算其面积
  public static double mianji(double a,double b,double c) {
    double s,l;
    l=(a+b+c)/2;
    s=Math.sqrt(l*(l-a)*(l-b)*(l-c));
    return s;
  }
  public static void main(String[] args) {
    double a,b,c,s;
    int q;
    System.out.println("请输入三条边长");
    Scanner in=new Scanner(System.in);
    a=in.nextDouble();
    b=in.nextDouble();
    c=in.nextDouble();
    q=panduan(a, b, c);
    if(q==1) {
      s=mianji(a, b, c);
      System.out.println("三角形的面积为:"+s);
          
    }
    else {
      System.out.println("输入边长有误,其不构成三角形");
    }
  }

}
//5某幼儿园只收2~6岁的小孩,2岁入小班,3~4岁入中班,5~6岁入大班
//输入小孩岁数,输出入哪类班
package calsswork3;

import java.util.Scanner;

public class test3_5 {
    //年龄和班级匹配,用switch语句
  public static String pp(int x) {
    String z="";
    switch(x) {
    case 0:
    case 1:{z="年龄不符合,不招生";break;}
    case 2:{z="小班";break;}
    case 3:
    case 4:{z="中班";break;}
    case 5:
    case 6:{z="大班";break;}
    default:{z="年龄不符合,不招生";}
      
    }
    return z;
  }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
      System.out.println("请输入小孩的年龄:");
      Scanner in=new Scanner(System.in);
      int x=in.nextInt();
      System.out.println("该小孩应入的班级为:"+pp(x));
  }

}
//6用if实现下面的计算功能
package calsswork3;

import java.util.Scanner;

public class test3_6 {
    //if函数
  public static double jisuan1(double x) {
    if(x<0) {
      return 2*x+1;
    }
    else if(x>=10) {
      return 4*x-4;
    }
    else {
      return x*x;
    }
  }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
      System.out.println("请输入一个数据:");
      Scanner in=new Scanner(System.in);
      double x=in.nextDouble();
      System.out.println("计算后的值为:"+jisuan1(x));
  }

}
//7输入三个整数,从大到小输出
package calsswork3;

import java.util.Scanner;

public class test3_7 {
    public static void sort(int a,int b,int c) {
      int max=b,min=a;
      if(a>b) {
         max=a;
         min=b;
      }
      if(c>max) {
        max=c;
      }
      if(min>c) {
        min=c;
      }
      System.out.println("从大到小的分别为:");
      System.out.println(max+" "+(a+b+c-max-min)+" "+min);
    }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
        System.out.println("请输入三个整数:");
        Scanner in=new Scanner(System.in);
        int a,b,c;
        a=in.nextInt();
        b=in.nextInt();
        c=in.nextInt();
        sort(a, b, c);
  }

}
//8输入三个数,求其平均值,输出大于平均值的数
package calsswork3;

import java.util.Scanner;

public class test3_8 {
    //求平均值
  public static double avg(double a,double b,double c) {
    return (a+b+c)/3.0;
  }
  //判断是否大于平均值
  public static void pd(double a,double b,double c) {
    double avg=avg(a,b,c);
    if(a>avg) {
      System.out.println(a+"大于平均值");
    }
      if(b>avg) {
      System.out.println(b+"大于平均值");
    }
      if(c>avg) {
      System.out.println(c+"大于平均值");
    }
  }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
       System.out.println("请输入三个数:");
       Scanner in=new Scanner(System.in);
       double a,b,c;
       a=in.nextDouble();
       b=in.nextDouble();
       c=in.nextDouble();
       System.out.println("这三个数的平均值为:"+avg(a, b, c));
       pd(a, b, c);
  }

}
//9随机产生50个1~100之间的整数,输出其中最小的数
package calsswork3;

public class test3_9 {
  public static int suiji(int n) {
    int a[]=new int[n];//用数组保存随机产生的数
    System.out.println("随机产生的"+n+"个数:");
    for(int i=0;i<n;++i) {
      int rnum=(int)(Math.random()*100+1);//random的范围是[0,1)      
      System.out.println(rnum);
      a[i]=rnum;
    }
    int min=100;
    //求最小数
    for(int i=0;i<a.length;++i) {
      if(min>a[i]) {
        min=a[i];
      }
    }
    return min;
  }
  public static void main(String[] args) {
    int n=50;
    System.out.println("最小数为:"+suiji(n));
  }
}
//10求100以内所有奇数和(分别用for,do-while,while循环实现)
package calsswork3;

public class test3_10 {
    //求奇数和
  //for循环实现
  public static int oddsum1(int n) {
    int i,t=0;
    for(i=0;i<n;++i) {
      if(i%2!=0) {
        t+=i;
      }
    }
    return t;
  }
  //do-while循环实现
  public static int oddsum2(int n) {
    int i=0,t=0;
    do {
      if(i%2!=0) {
        t+=i;
      }
      ++i;
    }
    while(i<n);
    return t;
  }
  //while循环实现
  public static int oddsum3(int n) {
    int i=0,t=0;
    while(i<n) {
      if(i%2!=0) {
        t+=i;
      }
      ++i;
    }
    return t;
  }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
       int n=100;
       System.out.println("100以内的奇数和为:"+oddsum1(n));
       System.out.println("100以内的奇数和为:"+oddsum2(n));
       System.out.println("100以内的奇数和为:"+oddsum3(n));
  }

}
//11输出100~200间所有不能被3和4整除的数
package calsswork3;

public class test3_11 {
    public static void zhengchu() {
      for(int i=100;i<=200;++i) {
        if(i%3!=0&&i%4!=0) {
          System.out.println(i);
        }
      }
    }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
        System.out.println("100~200间所有不能被3和4整除的数");
        zhengchu();
  }

}
//12找出100~200间满足其各位数字之和等于6
package calsswork3;

public class test3_12 {
  public static void shuzihe() {
      for(int i=100;i<=200;++i) {
        if(i%10+i/10%10+i/100==6) {
          System.out.println(i);
        }
      }
    }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
      System.out.println("100~200间满足其各位数字之和等于6的数为:");
      shuzihe();
  }

}
//13输入包括两个运算量和一个运算符的算术表达式,计算并输出运算结果
package calsswork3;

import java.util.Scanner;

public class test3_13 {
    public static void fun(double x,char a,double y) {
      switch(a) {
      case '+':{
        System.out.println(x+"+"+y+"="+(x+y));break;
      }
      case '-':{
        System.out.println(x+"-"+y+"="+(x-y));break;
      }
      case '*':{
        System.out.println(x+"*"+y+"="+(x*y));break;
      }
      case '/':{
        System.out.println(x+"/"+y+"="+(x/y));break;
      }
      }
    }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
       System.out.println("请输入运算符和数值,如:a + b");
       double x,y;
       char a;
       Scanner in=new Scanner(System.in);
       x=in.nextDouble();
       a=in.next().charAt(0);
       y=in.nextDouble();     
       fun(x, a, y);
  }

}
//14输入年份和月份,输出该月的天数
package calsswork3;

import java.util.Scanner;

public class test3_14 {
    public static String tianshu(int y,int m) {
      String z="";
      switch(m) {
      case 1:
      case 3:
      case 5:
      case 7:
      case 8:
      case 10:
      case 12:{
        z="该月有31天";break;
      }
      case 2:
        if(y%4==0&&y%100!=0||y%400==0) {
          z="该月有29天";break;
        }
        else {
          z="该月有28天";break;
        }
      case 4:
      case 6:
      case 9:
      case 11:{
        z="该月有30天";break;
      }
      }
      return z;
    }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
     System.out.println("请输入年份和月份:");
     Scanner in=new Scanner(System.in);
     int y=in.nextInt();
     int m=in.nextInt();
     System.out.println(tianshu(y, m));
  }

}
//15分别用for,while,do-while三种循环语句计算一个正数的阶乘
package calsswork3;

import java.util.Scanner;

public class test3_15 {
    //for循环实现
  public static long jiecheng1(int x) {
    long t=1;
    if(x==0) {
      return t;
    }
    for(int i=1;i<=x;++i) {
      t=t*i;
    }
    return t;
  }
  //while循环实现
  public static long jiecheng2(int x) {
    long t=1;
    int i=1;
    if(x==0) {
      return t;
    }
    while(i<=x) {
      t*=i;
      ++i;
    }
    return t;
  }
  //do-while循环实现
  public static long jiecheng3(int x) {
    long t=1;
    int i=1;
    if(x==0) {
      return t;
    }
    do {
      t*=i;
      ++i;
    }
    while(i<=x);
    return t;
  }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
       System.out.println("请输入一个正数:");
       Scanner in=new Scanner(System.in);
       int x=in.nextInt();
       System.out.println(x+"的阶乘结果为:"+jiecheng1(x));
       System.out.println(x+"的阶乘结果为:"+jiecheng2(x));
       System.out.println(x+"的阶乘结果为:"+jiecheng3(x));
  }

}
//16设计程序,从输入数据中统计正整数和负整数的个数.用输入0来结束
package calsswork3;

import java.util.Scanner;

public class test3_16 {
    public static void jishu(int n) {
    int i=0,j=0;
    while(n!=0) {
      if(n>0) {
        ++i;
      }
      else {
        ++j;
      }
      Scanner in=new Scanner(System.in);
        n=in.nextInt();
    }
    System.out.println("正数的个数为:"+i);
    System.out.println("负数的个数为:"+j);
  }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
       System.out.println("请输入一段数据并以0结束:");
       Scanner in=new Scanner(System.in);
     int n=in.nextInt();
       jishu(n);
  }

}