java实践
例3-4
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.printf("%d月是属于第一季度",n);
break;
case 4:
case 5:
case 6:System.out.printf("%d月是属于第二季度",n);
break;
case 7:
case 8:
case 9:System.out.printf("%d月是属于第三季度",n);
break;
case 10:
case 11:
case 12:System.out.printf("%d月是属于第四季度",n);
break;
default:System.out.printf("%d不代表月份",n);
}
}
}
例3-5
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);
}
}
例3-6
public class Example3_6{
public static void main(String args[]){
int sum,j,i;
for(i=0;i<=1000;i++){
for(j=1,sum=0;j<=i/2;j++){
if(i%j==0){
sum=sum+j;
}
}
if(sum==i){
System.out.printf("%8d是一个完数%n",i);
}
}
}
}
例3-7
public class Example3_7{
public static void main(String args[]){
int sum=0,i=0,max=8888,number=7;
while(true){
i++;
sum=sum+i;
if(sum>=max)
break;
}
System.out.println("1+2+.....n<"+max+"的最大整数n:"+(i-1));
for(i=1,max=200,sum=0;i<=max;i++){
if(i%number!=0){
continue;
}
sum=sum+i;
}
System.out.println(max+"之内能被"+number+"整除的数字之和是:"+sum);
}
}
例3-8
import java.util.*;
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.print("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(n+"不在数组中");
else
System.out.print(n+"是数组中的第"+middle+"个元素");
}
}