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C# Intermediate C# Polymorphism Virtual Methods

Matt Adams
Matt Adams
4,856 Points
Posted by Matt Adams
Matt Adams
4,856 Points

Need help resolving CS0161 and CS0162 errors.

Not sure what I'm doing wrong here (probably being too complex doing the comparison of any two values in the array.) . See attached for the code. Here is the error message: RepeatDetector.cs(5,30): error CS0161: `Treehouse.CodeChallenges.RepeatDetector.Scan(int[])': not all code paths return a value RepeatDetector.cs(11,17): warning CS0162: Unreachable code detected Compilation failed: 1 error(s), 1 warnings

Any help is greatly appreciated. Thanks!

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)
        {
            int seqCompare = 0;
            foreach(int i in sequence)
            {
                return sequence[i] == seqCompare;
                seqCompare = sequence[i];
            }
        }
    }
}

2 Answers

KEVIN WILLIAMS
KEVIN WILLIAMS
1,375 Points
KEVIN WILLIAMS
KEVIN WILLIAMS
1,375 Points

I'm not sure why it reports "not all code paths return a value", but your issue is with the return keyword: it forces you to exit the function immediately.

you want to store the result of your comparison in a variable, check that variable and then decide if you return true or false

Matt Adams
Matt Adams
4,856 Points
Matt Adams
Matt Adams
4,856 Points

Thanks, makes sense.

I modified it as so:

namespace Treehouse.CodeChallenges { class RepeatDetector : SequenceDetector { public override bool Scan(int[] sequence) { int seqCompare = 0; foreach(int i in sequence) { bool result = sequence[i] == seqCompare; if(result) { return true; } seqCompare = sequence[i]; } } } }

That eliminated the CS0162, but still getting the CS0161.

William Schultz
William Schultz
2,926 Points
William Schultz
William Schultz
2,926 Points

You need another return statement after your foreach loop. The code path that doesn't return a value is the path the code can take if your foreach loop never runs (as in the case that the sequence sent to the Scan method was null). Therefore, after the foreach loop and before closing your Scan method you need to add return false;