Read a string, separate it, and put it into an array C#

Question

I am trying to read in a string via input from the user and store it in an array. The string must be single digit numbers separated by a space. The user will enter exactly 20 numbers and no number can occur twice in a row.

Example string:

1 2 9 6 3 2 4 5 8 1 3 6 4 7 8 2 1 9 6 3

Here is the code I have to do this, as well as error check and it's not working properly. I think I am way over thinking the error checking. refString is an int array of size 20 in the code below.

case 2:
bool validated = false;
Console.WriteLine("\nPlease enter a 20 character reference string, each separated by a single space");
Console.WriteLine("A number should not occur twice in a row, ex: 1 5 4 4 6");
Console.WriteLine("Each character must be an integer 1-9");
Console.WriteLine("Example reference string:  1 2 3 4 2 1 5 6 2 1 2 3 7 6 3 2 1 2 3 6");
Console.WriteLine("\nEnter reference string:  ");
string s = Console.ReadLine();
refString = s.Split(' ').Select(n => Convert.ToInt32(n)).ToArray();  //split string and add numbers into array
int totalCount = refString.Length;

//if the user entered exactly 20 numbers, check to see if any of the numbers occur twice in a row
if (totalCount == 20)
{
    for (i = 1; i < 20; i++)
    {
        while (refString[i] == refString[i - 1])    //make sure two of the same number side by side do not occur
        {
            break;
        }

    }
}

while (totalCount != 20 || !validated)
{
    for (i = 1; i < 20; i++)
    {
        while (refString[i] == refString[i - 1])    //make sure two of the same number side by side do not occur
        {
            Console.WriteLine("\nError: reference string is NOT 20 numbers");
            Console.WriteLine("\nEnter reference string:  ");
            s = Console.ReadLine();
            refString = s.Split(' ').Select(n => Convert.ToInt32(n)).ToArray();
            totalCount = refString.Length;
        }
    }
    if (totalCount == 20)
    {
        for (i = 1; i < 20; i++)
        {
            while (refString[i] == refString[i - 1])    //make sure two of the same number side by side do not occur
            {
                break;
            }
        }
    }

}

break;
}

Rustkill · Accepted Answer · 2013-11-21 05:13:15Z

Try something like:

case 2:
    bool correctNumber = true;
    bool repeats = false;
    Console.WriteLine("\nPlease enter a 20 character reference string, each seperated by a single space");
    Console.WriteLine("A number should not occur twice in a row, ex: 1 5 4 4 6");
    Console.WriteLine("Each character must be an integer 1-9");
    Console.WriteLine("Example reference string:  1 2 3 4 2 1 5 6 2 1 2 3 7 6 3 2 1 2 3 6");
    Console.WriteLine("\nEnter reference string:  ");
    string s = Console.ReadLine();
    refString = s.Split(' ').Select(n => Convert.ToInt32(n)).ToArray();  //split string and add numbers into array
    correctNumber = refString.Length == 20;

    if (correctNumber)
    {
        for (i = 1; i < 20; i++)
        {
            if(refString[i] == refString[i - 1])
            {
                repeats = true;
                break;
            }
        }
    }
    else
    {
        Console.WriteLine("Error: reference string is NOT 20 numbers");
    }
    if (repeats)
    {
        Console.WriteLine("Error: reference string contains repeated numbers");
    }

    break;

That will check for the two fail conditions and output relevant messages.

Thank you for your reply. I was able to get it working and most error checking accomplished. The only thing I don't have done for the error handling is protecting against bad input such as if the user enters letters and also if the user enters a two digit number. Would you mind explaining how to do so? isNaN?

Anirudha · Accepted Answer · 2013-11-21 05:10:44Z

0

You can use regex to check if there are two contiguous repeating digits

if(!Regex.IsMatch(n,@".*(\d) \1.*"))
    s.Split(" ").Select(x=>int.Parse(x));

edited Nov 21, 2013 at 5:10

answered Nov 21, 2013 at 5:05

Anirudha

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Comments

Julián Urbano · Accepted Answer · 2013-11-21 05:22:36Z

bool correct = false;
while(!correct){
    // ask for numbers until correct
    Console.WriteLine("\nEnter reference string:  ");
    string s = Console.ReadLine();
    refString = s.Split(' ').Select(n => Convert.ToInt32(n)).ToArray();
    int totalCount = refString.Length;

    // check    
    if (totalCount == 20) {
        correct = true;
        for (i = 1; i < refString.Length; i++) {
            if(refString[i] == refString[i - 1]) {
                // consecutive number
                Console.WrinteLine("Error: same consecutive number "+refString[i]);
                correct = false;
                break;
            }
        }
    }else{
        Console.WrinteLine("Error: not 20 elements");
    }
}

Baldrick · Accepted Answer · 2013-11-21 05:40:07Z

One trick you can do is use Linq to filter out all the bad values, then check the count hasn't dropped below 20:

var listOfInts = stringTest.Split(' ').Select(n => Convert.ToInt32(n)).ToList();

// filter ints with adjacent values and out of range
var count =
    listOfInts.Where((i, j) => (j + 1 == listOfInts.Count || // adjacent values
                                i != listOfInts[j + 1]) 
                                && i > 0 && i < 10) // out of range
              .Count(); // total

If count < 20, then you know something was invalid (either out-of-range or next to an identical value).

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