CODEWITHSUNDEEP
arraysvb.netstring
Toby
Toby

Reputation: 10144

Check if string array contains non-empty strings without loop

I have an If statement that checks a number of things (BaySlots() is an array of strings). 

If (Not BaySlots.Contains(Not String.Empty)) OrElse
        (Not BayAcId = 0 AndAlso Not BayAcId = acProgramId _
            AndAlso overrideSetting = False) Then

I though the Array.Contains method of the first condition would be sufficient to tell me if the array held only empty strings, but it gives InvalidCastException: Conversion from string "" to type Long is not valid so I'm guessing Not String.Empty is actually evaluated to something that is attempted to be converted to a Long.

Is there a better method I can use to retro-fit this If, so that I can still include the test for only empty strings in the array, as part of the If, rather than having to add a preceding loop to test each index of BaySlots() for an empty string?

I thought there should probably be some way of testing this other than looping as that would be a relative lot of work just to test if there was no content.

Thanks

PS just to clarify this is not to test if the array has zero dimensions or is equal to Nothing but that the strings it does contain are all equal to String.Empty.

Upvotes: 4

Views: 2130

Answers (1)

Heinzi
Heinzi

Reputation: 172220

LINQ's Enumerable.Any can do this. A direct translation of your Not Contains(Not String.Empty))would be:

If (Not BaySlots.Any(Function(x) x <> "")) OrElse ...

(Feel free to replace "" with String.Empty, if that's what you prefer.)

Since you have a double negation here, I suggest to replace it with Enumerable.All for readability:

If BaySlots.All(Function(x) x = "") OrElse ...

This also communicates your intent more clearly ("If all entries are empty...").

Note: In VB.NET, comparing a string to "" or String.Empty also yields True if the string is Nothing.

Upvotes: 4

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