CODEWITHSUNDEEP
c#arraysstring
Leron
Leron

Reputation: 9866

C# - find the position of a string inside a predefined string array

I have a predefined string array with the letters from A to Q :

string[] SkippedAreasArray = new string[] {"A", "B", "C", "D", "E", "F", "G",
            "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q"};

In a TextBox inside Windows Form the user can enter skippedAreas like this: A,B,C,D... there is validations and restrictions to use only letters and commas so the input is guaranteed to be in this format.

What I do is taking the user input and populate another string array:

string[] SkippedAreasFromForm = new string[17];
...
SkippedAreasFromForm = (txtSkippedAreas.Text).Split(',');

Now comes the tricky part for which I'm seeking assistance. The user must enter Number of areas for example - 3. Which mean he is working only with A, B, and C. If the number of areas was 2 then he can only use A and B if the number of areas was 4 then A, B, C and D are available and so on.

What I need is to check if in the array SkippedAreasFromForm which is populated with the user input there is an area that doesn't match the above criteria.

What this mean in terms of coding - I need to take every element from SkippedAreasFromForm, take it's integer value from the predefined SkippedAreasArray and see if this value is equal or greater (>=) of the value that he entered as `Number of areas. If there is an area which is outside the scope of the selected number an error should be shown.

What I have right now is :

foreach (string tempAreaValue in SkippedAreasFromForm)
                {
                    for (int i = 0; i < SkippedAreasArray.Length; i++)
                    {
                        if (tempAreaValue == SkippedAreasArray[i])
                        {
                            if ((i + 1) > entity.AreasCnt)
                            {
                                MessageBox.Show("You must use areas only within the Number of Areas scope!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                                txtSkippedAreas.Focus();
                                return false;
                            }
                        }
                    }
                }

For the few test I made it works. But first - at least for me it seems over complicated. Second - I'm not sure that this algorithm is working exactly as I need to or I'm just having correct results by luck. Third - I'm coding C# for 2months now and this seems to me like an excellent candidate for a LINQ expression - do you think it would be better using LINQ and I would appreciate a help in the transformation.

Upvotes: 0

Views: 766

Answers (2)

Habib
Habib

Reputation: 223257

If you are looking for the elements in the array from start index to max string elements based on areaNumber, then:

int areaNumber = 4;
var result = SkippedAreasArray.Select((r, i) => new { Value = r, Index = i })
                              .Where(r => r.Index <= areaNumber - 1)
                              .Select(r => r.Value)
                              .ToArray();

For areaNumber 4 you will get "A", "B", "C", "D"

EDIT:

I'm looking if every element from the user input (which is array A,C,H,Q..) is inside the area determined from the areNumber (from comment)

Suppose your userInputArray is:

string[] userInputArray = new string[] {"A", "C", "H", "Q"};

Then you can use Enumerable.Except in the following manner:

if(result.Except(userInputArray).Any())
{
  //Invalid
}
else
{
 //Valid
}

Upvotes: 1

Jon Skeet
Jon Skeet

Reputation: 1500525

I think you're just looking for IndexOf:

int index = SkippedAreasArray.IndexOf(tempAreaValue);
if (index >= entity.AreasCnt)
{
    ...
}

(You might also want to check for index being -1, which would occur if the element wasn't in the list at all. Also, consider duplicates - can the user enter A, A, A?)

Upvotes: 5

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