c++ - 数字を単語に変換する

Question

私は C++ の初心者で、数字を 0 から 99 までの単語に出力するプログラムを作成しました。プログラムは正常に動作していますが、10 から 20 までの数字が間違った出力を示しています。

    #include<iostream>
    using namespace std;
    main()
    {
        int number,digit_1,digit_2;
        cout<<"Please enter a number between 0-99: ";
        cin >> number;
        digit_1=number/10;
        digit_2=number%10;
        if(number>=10 && number<=19)
        {
        switch(number)
        {
            case 10: cout<<"Ten"; break;    
            case 11: cout<<"Eleven"; break; 
            case 12: cout<<"Twelve"; break; 
            case 13: cout<<"Thirteen"; break;
            case 14: cout<<"Fourteen"; break;
            case 15: cout<<"Fifteen"; break;
            case 16: cout<<"Sixteen"; break;
            case 17: cout<<"Seventeen"; break;
            case 18: cout<<"Eighteen"; break;
            case 19: cout<<"Nineteen"; break;
        }
        }
        switch(digit_1)
        {
            case 2: cout<<"Twenty"; break;
            case 3: cout<<"Thirty"; break;  
            case 4: cout<<"Forty"; break;   
            case 5: cout<<"Fifty"; break;   
            case 6: cout<<"Sixty"; break;   
            case 7: cout<<"Seventy"; break;
            case 8: cout<<"Eighty"; break;
            case 9: cout<<"Ninety"; break;
        }
            switch(digit_2)
        {
            case 0: cout<<" Zero"; break;
            case 1: cout<<" One"; break;    
            case 2: cout<<" Two"; break;    
            case 3: cout<<" Three"; break;
            case 4: cout<<" Four"; break;
            case 5: cout<<" Five"; break;
            case 6: cout<<" Six"; break;
            case 7: cout<<" Seven"; break;
            case 8: cout<<" Eight"; break;
            case 9: cout<<" Nine"; break;
        }
    }

出力：-

0 ～ 99: 12 の数字を入力してください

12 2