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C# Intermediate C# Polymorphism Virtual Methods

Posted by veronica Robinson
veronica Robinson
7,692 Points

Need help with this challenge.

What am I doing wrong here??

Override the Scan method to return true if any value in the array is a repeat of the value immediately preceding it.

SequenceDetector.cs 
namespace Treehouse.CodeChallenges
{
    class SequenceDetector
    {
        public virtual bool Scan(int[] sequence)
        {
            return true;
        }
    }
}
RepeatDetector.cs 
namespace Treehouse.CodeChallenges
{
    class RepeatDetector : SequenceDetector
    {
       public override bool Scan(int[] sequence)
        { 
           for(int i=0; i < sequence.Length; i++)
           {
        if(sequence[i] == sequence[i-1])
        {


           return true;
       }
           }
       }
    }
}

1 Answer

tjgrist
tjgrist
6,553 Points
tjgrist
tjgrist
6,553 Points

You're close! 

namespace Treehouse.CodeChallenges
{
    class RepeatDetector : SequenceDetector
    {
        public override bool Scan(int[] sequence)
        {  
              for(int i=1; i < sequence.Length ; i++)
              { 
                   if(sequence[i] == sequence[i - 1])
                   {
                        return true;
                   }
              }
              return false;
        }
   }
}
tjgrist
tjgrist
6,553 Points

Do you see the problem? In the for loop, you need to start the 'i' counter at 1 instead of at 0, so that you can do a 

sequence[i - 1]

on the sequence and you won't get an indexOutOfRangeException.