title: "Wrong number of indices inside [];expected 2" error for two-dimensional array in C#
body: <p>Hi I am a beginner c# learner, I did something wrong here as I know, but can't figure out where, anybody knows?</p>
  
  <pre><code>namespace translateTelNum
  {
  public partial class Form1 : Form
  {
      public Form1()
      {
          InitializeComponent();
      }
  
      private void button1_Click(object sender, EventArgs e)
      {
          String originalContent = "";
          originalContent = box1.Text.ToUpper();
  
          char[,] charGroup = new char[,]
         {
          {'A','B','C' }, 
          {'D','E','F' },              
          {'G','H','I' }, 
          {'J','K','L' }, 
          {'M','N','O' },
          {'P','R','S' }, 
          {'T','U','V' }, 
          {'W','X','Y' } 
         };
  
          String numbers = "";
  
          for (int i = 1; i &lt;= originalContent.Length; i++)
          {
              for (int a = 1; a &lt;= charGroup.Length; a++)
              {
                  for (int b = 1; b &lt;= charGroup[a].Length; b++)
                  {
                      if (originalContent[i] == charGroup[a][b])
                      {
                          numbers += a + 2;
                      }
                  }
              }
              if (i == 2 &amp;&amp; i== 7)
              {
                  numbers += "-";
              }
          }
  
          Console.WriteLine(numbers);
      }
  }
  }
  </code></pre>
  
  <hr>
  
  <p>Error "Wrong number of indices inside [];expected 2" for the following lines:</p>
  
  <pre><code>for (int b = 1; b &lt;= charGroup[a].Length; b++)
      if (originalContent[i] == charGroup[a][b])
  </code></pre>