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c#vb.netstringtrim
Jonesopolis
Jonesopolis

Reputation: 25370

C# to VB - TrimStart Behavior

I have the simplest VB code:

Dim test As String = "DDN8057"
Console.WriteLine(test.TrimStart("DDN"))

gives me

N8057

Why? Converting this to C# (which I'm far more familiar with), made me realize that TrimStart actually expects a params char[], but running

Console.WriteLine("DDN8057".TrimStart("DDN".ToCharArray()));

gives me my expected

8057

So, I guess VB is capable of treating a string as a char array internally (is this true?), but why the discrepancy in my output?

Upvotes: 2

Views: 1727

Answers (1)

Matt Wilko
Matt Wilko

Reputation: 27322

You do not have Option Strict switched On in your VB project.

I can tell because test.TrimStart("DDN") does not compile when this is on. This is because as you correctly pointed out TrimStart expects an explicit char array (or a single char)

What happens when you run this with Option Strict Off is the compiler coerces the String (DDN) into a single char (D) (this is an implicit narrowing conversion which Option Strict expressly forbids) which is why you get N8057 as your output.

You would think that as a string is just a char array it would convert it to an array but it doesn't - it effectively performs CChar("DDN")!

Conclusion

Option Strict On = Good. Here is how to switch it on by default: Option Strict on by default in VB.NET

Upvotes: 3

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