Truncate string

A string contains the letters "abcdef." But we just want the first 3 letters. We can truncate the string with a special Function.

With an inner Substring call, we can implement string truncation. We must first check the desired length to ensure it will not cause Substring to throw an exception.

Example code

Here is our Truncate implementation. The Main Sub calls the Truncate Function with some example strings. It specifies a string and a length.

Module Module1

    Public Function Truncate(value As String, length As Integer) As String
        ' If argument is too big, return the original string.
        ' ... Otherwise take a substring from the string's start index.
        If length > value.Length Then
            Return value
        Else
            Return value.Substring(0, length)
        End If
    End Function

    Sub Main()
        ' Test the Truncate method with these two strings.
        Dim test1 As String = "ABC"
        Dim test2 As String = "ABCDEF"

        Dim result = Truncate(test1, 2)
        Console.WriteLine("2=" + result)

        Console.WriteLine("4=" + Truncate(test2, 4))
        Console.WriteLine("100=" + Truncate(test2, 100))
    End Sub

End Module
2=AB
4=ABCD
100=ABCDEF

A logical step

In Truncate, we have an If-statement. We cannot use Substring with a length that is beyond the end of our string. So we ensure our "length" argument is not too large.

String truncation ensures a string does not exceed a certain number of characters. It does not provide padding to a specific character count.