Visual Basic .NET

The InStr() Method in VB .NET

The InStr( ) method of string variables tells you what the position
of one string is inside another. For example, if your string was “me@me.com
and you wanted to know if the string contained the @ symbol, you could
use InStr( ) Method. You would use it like this

The InStr( ) method of string variables tells you what the position
of one string is inside another. For example, if your string was “me@me.com
and you wanted to know if the string contained the @ symbol, you could
use InStr( ) Method. You would use it like this

FirstString = “me@me.com”
SecondString = “@”

position = InStr( FirstString, SecondString
)

The variable FirstString is the string we want to search; SecondString
is what we want to search for. You can specify a starting position for the search
to begin. If you do, this number goes at the start (the default is zero):

position = InStr( 1, FirstString,
SecondString )

The variable called position has to be an integer variable. That’s because
the InStr() Method returns a number, and not text. In the code above,
position would have a value of 3. That’s because the @ symbols
starts at the third letter of “me@me.com”.

(Note: the InStr() Method starts counting at 1, and not zero like Chars(),
which is very confusing!)

If the string you’re searching for is not found, then the value placed inside
of your integer variable (position in our case) is zero. That enables
you to code something like this:

If position = 0 Then

MessageBox.Show(“Not a Valid email address: There
was No @ Sign”)

End If

Another useful string method is Substring. We’ll see how to use it in the next
part.

Kaynak : https://www.homeandlearn.co.uk/NET/nets7p4.html ‘sitesinden alıntı

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