CODEWITHSUNDEEP
vb.netarrayscontains
user1298311
user1298311

Reputation:

To check if array consist of only elements from another array, VB.NET

Working with a Visual Basic.NET console application that features a VERY BASIC natural language recognition function-it only has to work with specific fields of words so it wasn't that hard. I got the logic all lay out on paper, but I've encountered a problem.

I want the application to check if the user input is only consist of valid words.

When the user inputs something, I used a function to cut it down to only alphanumeric characters, and used the string.split method to create an array that contains separate words the user input. What I wish to do now is to compare the input array to another array (a full set of valid words), and return an error message if the input array contains only elements that exist in the valid words array.

For instance, if all valid words are "ALPHA", "BETA" and "GAMMA". When the use inputs something like "ALPHA BETA"-the program will accept the input. If the input is "APPLES" then it will return an error message because the string APPLE is not a member of the valid words array.

I hope I've made my question clear enough, anyone please help. Thanks.

Upvotes: 2

Views: 3136

Answers (4)

user774411
user774411

Reputation: 1809

In your case, it is not necessary to use array as data structure. Instead, you can store your list of valid words in System.Collections.Specialized.NameValueCollection class. Then, you can test each user input against the list of valid words that stored in System.Collections.Specialized.NameValueCollection class.

How to store valid word in System.Collections.Specialized.NameValueCollection class: See this.

How to check if there is valid word entry in System.Collections.Specialized.NameValueCollection class: See this

Upvotes: 1

Timiz0r
Timiz0r

Reputation: 1324

You could use a HashSet(T) to store your allowed words. HashSet.Contains is an O(1) operation rather than an O(n) found in other collections, which makes a HashSet(T) more efficient.

Private Shared AllowedWords As New HashSet(Of String)(StringComparer.OrdinalIgnoreCase) From
    {
        "Alpha", "Beta", "Gamma"
    }

Public Shared Function WordsAreValid(ParamArray words() As String) As Boolean
    For Each word As String In words
        If Not AllowedWords.Contains(word) Then Return False
    Next

    Return True
End Function

Upvotes: 1

pingoo
pingoo

Reputation: 2064

I'd use Except, http://msdn.microsoft.com/en-us/library/bb300779.aspx 

Private AllowedWords As String() = {"these", "are", "good", "words"}

Sub Main()

    Dim badUserInput As String() = {"these", "are", "bad", "words"}

    Dim badWords As IEnumerable(Of String) = badUserInput.Except(AllowedWords)

    If badWords.Any Then
        '  User has entered a disallowed word 
        Throw New ArgumentException(String.Format("Words '{0}' are not allowed", String.Join(",", badWords)))
    End If

End Sub

I also wrote a blog on different ways to join collections a while ago:

http://dotnetrene.blogspot.co.uk/2012/01/joining-collections-in-linq-contains-vs.html

Upvotes: 2

sloth
sloth

Reputation: 101042

Maybe you are looking for something like the All()-Method, which checks if each element in a collection satisfies a condition. Consider the following example:

Dim validWords = {"ALPHA", "BETA", "GAMMA"}

Dim thisIsNotValid = {"ALPHA", "APPLES"}.All(Function(word) validWords.Contains(word))

Dim thisIsValid = {"ALPHA", "BETA"}.All(Function(word) validWords.Contains(word))

thisIsNotValid will evaluate to False, and thisIsValid will evaluate to True.

Upvotes: 3

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