c++ - 电话词生成器帮助 C++

Question

我有一些作业一直在完成，直到我到达最后一步，现在我被难住了，我真的很感激你的帮助。

该项目的前提是创建一个包含给定电话号码的可能单词的文件。用户应输入格式为“###-####”的数字。然后代码将连字符拉出并将电话号码发送到方法 wordGenerator。我知道到目前为止一切正常。当输出单词的不同可能性时，我遇到了问题。这是我的方法:

// function to form words based on phone number
void wordGenerator( const int * const n )
{
  // set output stream and open output file
  /* Write a declaration for an ofstream object called
     outFile to open the file "phone.dat" */ 
 ofstream outFile("phone.dat");
 // letters corresponding to each number

  /* Write a declaration for an array of 10 const char *'s
  called phoneLetters. Use an initializer list to assign
  each element of the array the corresponding string of
  three letters. Use dummy characters for 0 and 1 */
  const char * phoneLetters[] = {"###", "###", "ABC", "DEF", "GHI",
                     "JKL", "MNO", "PRS", "TUV", "WXY"};
  // terminate if file could not be opened
  /* Write code to check if the file was opened successfully,
     and terminate if not */
   if( !outFile )
   {
    cerr << "The file could not be opened";
    exit(1);
   }

  int count = 0; // number of words found

  // output all possible combinations
  for ( int i1 = 0; i1 <= 2; i1++ )
  {
     for ( int i2 = 0; i2 <= 2; i2++ )
     {
        for ( int i3 = 0; i3 <= 2; i3++ )
        {
           for ( int i4 = 0; i4 <= 2; i4++ )
           {
              for ( int i5 = 0; i5 <= 2; i5++ )
             {
                for ( int i6 = 0; i6 <= 2; i6++ )
                 {
                   for ( int i7 = 0; i7 <= 2; i7++ ) 
                    {
                    /* Write a series of cascaded stream insertion
               operations to output a set of seven letters
           to outFile, followed by a space */

                     outFile << phoneLetters[i7 + 2] << phoneLetters[i6 + 2] <<  phoneLetters[i5 + 2]  << phoneLetters[i4 + 2] << phoneLetters[i3 + 2] << phoneLetters[i2 + 2]
                            << phoneLetters[i1 + 2] << ' ';
                    if ( ++count % 9 == 0 ) // form rows
                       outFile << '\n';
                   } // end for
                 } // end for
              } // end for
           } // end for
         } // end for
      } // end for
    } // end for

  // output phone number
    outFile << "\nPhone number is ";

    for ( int i = 0; i < 7; i++ ) 
    {
      if ( i == 3 )
      outFile << '-';

      outFile << n[ i ];
    } // end for

   /* Write a statement to close the ouput file */
     outFile.close();
     system("pause");
    } // end function wordGenerator

不幸的是，我得到了一个代码框架，并被告知要填写空白以完成作业。凡是注释被屏蔽的地方(/* */)都是我要填代码的地方。

我不确定我需要做什么来输出可能单词的正确格式。我尝试搜索谷歌，但我发现的所有结果都使用更简单(在我看来)的 switch 语句来实现这一点，我被模板限制了:(

感谢所有帮助，即使是朝着正确方向的插入。

编辑: 我只是想到了另一件事。我觉得如果有人甚至可以帮助我弄清楚如何单独而不是 block 地遍历 phoneLetters[] 的字符，那将是向前迈出的重要一步。 例子: 当读取电话号码的数字“2”而不是打印“ABC”时，为所有可能的组合打印“A”，然后转到“B”。

编辑: 这是我的 main():

int main()
{
  int phoneNumber[ 7 ] = { 0 }; // holds phone number

   // prompt user to enter phone number
   cout << "Enter a phone number (digits 2 through 9) "
     << "in the form: xxx-xxxx\n";

   // loop 8 times: 7 digits plus hyphen;
   // hyphen is not placed in phoneNumber
   for ( int u = 0, v = 0; u < 8; u++ ) 
  {
     int i = cin.get();

     // test if i is between 0 and 9
     if ( i >= '0' && i <= '9' )  
     phoneNumber[ v++ ] = i - '0';
   } // end for

   wordGenerator( phoneNumber ); // form words from phone number
   return 0;
} // end main

Answer 1

如果您无法摆脱可怕的嵌套 for 语句，那么您可以使用以下行:

outFile
    << phoneLetters[n[0]][i1]
    << phoneLetters[n[1]][i2]
    << phoneLetters[n[2]][i3]
    << phoneLetters[n[3]][i4]
    << phoneLetters[n[4]][i5]
    << phoneLetters[n[5]][i6]
    << phoneLetters[n[6]][i7]
    << ' ';

关于代码的一些其他说明:

• 避免在 C++ 中按原样使用 exit prevents destructors from running

• 避免 namespace pollution使用 using namespace 语句(我假设上面有一个 using namespace std; 语句)

• 如果您没有使用exit 并删除暂停(或添加范围)，那么explicit close of fstream is redundant

希望这对您有所帮助。