如何仅使用 while 和 if-else 循环转换为十六进制

Question

我必须仅使用标题中提到的循环将给定数字从十进制转换为十六进制。意思是没有 for 循环。到目前为止，一切都像转换 683 一样工作。它打印 2AB 没问题，而 34821 打印 8805。问题是当两位数之间需要一个整数时。例如，我无法将 31388 转换为 7A9C。我知道我的问题是什么，但我不知道如何解决它。

import java.util.Scanner;
public class Lab12abHexNumbersTEST
{
   public static void main(String[] args)
   {
     Scanner decimal = new Scanner(System.in);
     System.out.println("Enter a decimal number between 1 and 50,000: ");
     int num = decimal.nextInt();

     String hex1 = ""; 
     String letter = "";
     String hex3 = "";
     String hex_last = "";
     int dec = num;
     while (dec > 0)
     {
         hex1 = (dec % 16) + hex1;

         if(dec % 16 >= 9){
            hex1 = "";

            if(dec % 16 == 15) {
               letter = "F" + letter + hex1;
            } else if (dec % 16 == 14) {
               letter = "E" + letter + hex1;
            } else if (dec % 16 == 13) {
               letter = "D" + letter + hex1;
            } else if (dec % 16 == 12) {
               letter = "C" + letter + hex1;
            } else if (dec % 16 == 11) {
               letter = "B" + letter + hex1;
            } else if (dec % 16 == 10) {
               letter = "A" + letter + hex1;
            } 

            System.out.println(letter);
         }
         hex3 = hex1 + letter;

         dec = dec / 16;

      }

      hex_last = hex3; 
      System.out.println("The decimal number " + num + " in hexadecimal is " 
+ hex_last);
  }   
}

Answer 1

我已经提供了这个问题的解决方案。

注意：我使用 switch 语句使代码更清晰，但我相信您知道如何将它们转换回 if/else 情况。如果您需要帮助，请询问。

注意：我使用了StringBuilder 而不是直接使用字符串。您可以轻松地将它们更改为字符串，但我选择了 stringbuilder，因为它再次使代码更清晰。

public static void main(String[] args) {
        int dec = 31388 ;
        StringBuilder hexString = new StringBuilder();

        while (dec != 0){
            int hexDigit = dec%16; // obtain this remainder
            dec /= 16; //update dec

            if (hexDigit < 10) hexString.insert(0, hexDigit);
            else {
                switch (hexDigit) {
                    case 10 :
                        hexString.insert(0, "A");
                        break;
                    case 11 :
                        hexString.insert(0, "B");
                        break;
                    case 12 :
                        hexString.insert(0, "C");
                        break;
                    case 13 :
                        hexString.insert(0, "D");
                        break;
                    case 14 :
                        hexString.insert(0, "E");
                        break;
                    case 15 :
                        hexString.insert(0, "F");
                        break;
                    default: break;
            }
        }
    } // while
    System.out.println(hexString);
}

输出：7A9C

根据要求转换为 if/else 块：

else {
            if (hexDigit == 10) {
                hexString.insert(0, "A");
            } else if (hexDigit == 11) {
                hexString.insert(0, "B");
            } else if (hexDigit == 12) {
                hexString.insert(0, "C");
            } else if (hexDigit == 13) {
                hexString.insert(0, "D");
            } else if (hexDigit == 14) {
                hexString.insert(0, "E");
            } else if (hexDigit == 15) {
                hexString.insert(0, "F");
            }
        }

使用字符串，解决方法是：

public static void main(String[] args) {
    int dec = 31388;
    String answer = "";

    while (dec != 0){
        int hexDigit = dec%16; // obtain this remainder
        dec /= 16; //update dec

        if (hexDigit < 10) {
            answer = hexDigit + answer;
        }
        else {
            if (hexDigit == 10) {
                answer = "A" + answer;
            } else if (hexDigit == 11) {
                answer = "B" + answer;
            } else if (hexDigit == 12) {
                answer = "C" + answer;
            } else if (hexDigit == 13) {
                answer = "D" + answer;
            } else if (hexDigit == 14) {
                answer = "E" + answer;
            } else if (hexDigit == 15) {
                answer = "F" + answer;
            }
        }
    } // while
    System.out.println(answer);
}

Answer 2

如果允许字符串函数：

import java.util.*;

public static void main(String[] args){
    int dec = 31388 ;
    String digits = "0123456789ABCEDF";
    StringBuilder hexString = new StringBuilder();

    while(dec != 0){
        hexString.insert(0, digits.indexOf(dec % 16));
        dec /= 16;
    }

    System.out.println(hexString);
}

如何仅使用 while 和 if-else 循环转换为十六进制

How to Convert to Hexadecimal using only while and if-else loops

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