第三章程序实例

import java.util.*；
public class Example3_1{
  public static void main(String args[]){                　　
  Scanner reader = new Scanner(System.in);
  System.out.println("输入待移位的int型整数:");
  int x = reader.nextInt();
  System.out.println("输入位移量:");
  int n = reader.nextInt();
  System.out.println("左位移的结果:"+(x<<n));
  System.out.println("右位移的结果:"+(x>>n));
 }
}

 

 

 

 

public class Example3_2{
 public static void main(String args[]){
  char a[]={"金","木","水","火","土"};
  char secret='z';
  for(int i = 0; i < a.length; i++){
   a[i]=(char)(a[i]^secret);
   
  }
  System.out.println("密文:");
  for(int i = 0; i < a.length; i++){
   System.out.println(" "+a[i]);
  }
  for(int i = 0; i < a.length; i++){
   a[i] = (char)(a[i]^secret);
  }
  System.out.println("原文:");
  for(int i = 0; i < a.length; i++){
   System.out.println("  "+a[i]);
  }

 

 

 

 

import java.util.*;
public class Example3_2{
 public static void main(String args[]){
  Scanner reader = new Scanner(System.in);
  double a = 0, b = 0, c = 0;
  System.out.println("输入边a:");
  a = reader.nextDouble();
  System.out.println("输入边b:");
  b = reader.nextDouble();
  System.out.println("输入边c:");
  c = reader.nextDouble();
  if(a+b>c&&a+c>b&&b+c>a){
   if(a*a==b*b+c*c||b*b==a*a+c*c||c*c==a*a+b*b){
    System.out.println("构成直角三角形！");
   }
   else if(a*a<b*b+c*c&&b*b<a*a+c*c&&c*c<a*a+b*b){
    System.out.println("构成锐角三角形！");
   }
   else{
    System.out.println("构成钝角三角形！");
   }
  }
  else{
   System.out.println("不能构成三角形！");
  }
 }
}

 

 

 

import java.util.*;
public class Example3_4{
 public static void main(String args[]){
  Scanner reader = new Scanner(System.in);
  System.out.println("输入一个月份:");
  int n = reader.nextInt();
  switch(n){
   case 1:
   case 2:
   case 3:System.out.println(+n+"属于第一季度！");
    break;
   case 4:
   case 5:
   case 6:System.out.println(+n+"属于第二季度！");
    break;
   case 7:
   case 8:
   case 9:System.out.println(+n+"属于第三季度！");
    break;
   case 10:
   case 11:
   case 12:System.out.println(+n+"属于第四季度！");
    break;
  }
 }
}

 

 

 

public class Example3_5{
 public static void main（String args[]){
  double sum = 0; item = 1;
  int i = 1;
  while(i<=1000){
   sum = sum + item;
   i++;
   item = item*(1.0/i);
  }
  sum = sum + 1;
  System.out.println("e="+sum);
  sum = 0;
  i = 1;
  item = 1;
  do{
   sum = sum + item;
   i++;
   item = item*(1.0/i);
  }while(i<=1000);
  sum = sum + 1;
  System.out.println("e="+sum);
 }
}

 

 

 

public class Example3_6{
 public static void main(String args[]){
  int sum, i, j;
  for(i=1;i<=1000;i++){
   for(j=1,sum=0;j<=i/2;j++){
    if(i%j==0){
     sum = sum + j;
    }
   }
   if(sum==i){
    System.out.println(+i+" ");
   }
  }
 }
}

 

 

 

public class Example3_6{
 public static void main(String args[]){
  int sum, i, j;
  for(i=1;i<=1000;i++){
   for(j=1,sum=0;j<=i/2;j++){
    if(i%j==0){
     sum = sum + j;
    }
   }
   if(sum==i){
    System.out.println(+i+" ");
   }
  }
 }
}

 

 

 

public class Example3_7{
 public static void main(String args[]){
  int sum = 0,i = 0, max = 888, number = 7;
  while(true){
   i++;
   sum = sum + i;
   if(sum >= max)
    break;
  }
  System.out.println("the max number is :"+(i-1));
  for(i = 1, max = 200, sum = 0; i<=max;i++){
   if(i%number!=0){
    continue;
   }
   sum = sum + i;
  }
  System.out.println("the sum is :"+sum);
 }
}

 

 

import java.util.Scanner;
public class Example3_8{
 public static void main(String args[]){
  int n,start,end,middle;
  int a[]={-2,1,4,5,8,12,17,23,45,56,90,100};
  start = 0;
  end = a.length;
  middle = (start+end)/2;
  int count = 0;
  Scanner reader = new Scanner(System.in);
  System.out.println("请输入一个整数:");
  n = reader.nextInt();
  while(n!=a[middle]){
   if(n>a[middle]){
    start = middle;
   }
   else if(n < a[middle]){
    end = middle;
   }
   middle = (start+end)/2;
   count++;
   if(count>a.length/2)
    break;
  }
  if(count>a.length/2)
   System.out.println("不在数组中！");
  else
   System.out.println("是数组中第"+middle+"个元素");
 }
}