对/和%的应用的数字转英文练习java

题目描述

Jessi初学英语，为了快速读出一串数字，编写程序将数字转换成英文：

如22：twenty two，123：one hundred and twenty three。

 

说明：

数字为正整数，长度不超过九位，不考虑小数，转化结果为英文小写；

输出格式为twenty two；

非法数据请返回“error”；

关键字提示：and，billion，million，thousand，hundred。

 

方法原型：public static String parse(long num) 

 输入描述:

输入一个long型整数

输出描述:

输出相应的英文写法

示例1

输入

2356

输出

two thousand three hundred and fifty six

思路：1、由不超过九位数和英语中的读法，可以看出每三位处理一次；

          2、在11-19之间的读法和20-99读法不同，编程实现的话，需要把这些定义为静态数组来调用，同时在判断的时候分

               情况来讨论，注意对if和else的分类； 

          3、使用/来进行位的判断，使用%来截取后面的数字的部分；

          4、结构上有分主函数、题目要求的函数、转换数字为字符串的函数；

代码实现：

import java.util.*;
public class Main{

    public static String[] bit_num = {"zero","one","two","three","four","five","six","seven","eight","nine"};
     
    public static String[] ten_num = {"ten","eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen"};
     
    public static String[] twenty_more = {"twenty","thirty","forty","fifty","sixty","seventy","eighty","ninety"};
     
  
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        while(sc.hasNext()){
            Long n=sc.nextLong();
            String str=parse(n);
            System.out.println(str);
        }
        sc.close();
    }
      
    public static String parse(long num){
        if(num < 0) return "error";
        StringBuffer sb=new StringBuffer();
        long billion = num / 1000000000;
        if(billion != 0){
            sb.append(trans(billion) + " billion ");
        }
         
        num %= 1000000000;
        long million = num / 1000000;
        if(million != 0){
            sb.append(trans(million) + " million ");
        }
         
        num %= 1000000;       
        long thousand = num / 1000;
        if(thousand != 0){
            sb.append(trans(thousand) + " thousand ");
        }
         
        num %= 1000;       
        long hundred = num;
        if(hundred != 0){
            sb.append(trans(hundred));
        }
        return sb.toString().trim();//去掉首尾的空格
    }

    public static String trans(long num){
        StringBuffer sb = new StringBuffer();
        int h = (int)(num / 100);
        if(h != 0){
            sb.append(bit_num[h] + " hundred");
        }
         
        num %= 100;
        int t = (int)(num / 10);
        if(t != 0){
            if(h != 0){
                sb.append(" and ");
            }
            if(t == 1){
                sb.append(ten_num[(int)(num%10)]);
            }
            else{
                sb.append(twenty_more[(int)(t - 2)] + " ");
                if(num % 10 != 0){
                    sb.append(bit_num[(int)(num%10)]);
                }
            }
        }
        else if(num % 10 != 0){
            if(h != 0){
                sb.append(" and ");
            }
            sb.append(bit_num[(int)(num%10)]);
        }
        return sb.toString().trim();
    }
}