Converting char array into string array in VB.NET

Question

I am trying to convert an array of characters into a string array (where each character becomes a string), as I need it to be a string array for some processing on the array later in the program. Here is the code I am using:

Dim inputexpression As String = UCase(txtInput.Text)
Dim arrinputexpressionchar() As Char = inputexpression.ToCharArray()
Dim arrinputexpression() As String

For i = 0 To arrinputexpressionchar.Length
    arrinputexpression(i) = Char.ToString(arrinputexpressionchar(i))
Next

However, this throws up a 'NullReferenceException was unhandled' (Object reference was not set to an instance of an object) error. Why does this code not work?

Does the error state on which line the error occurs?

Tom Bowers
– Tom Bowers

2013-10-28 15:16:30 +00:00
Commented Oct 28, 2013 at 15:16 — Tom Bowers
– Tom Bowers, Commented Oct 28, 2013 at 15:16
You don't need i += 1 in a For loop.

bendataclear
– bendataclear

2013-10-28 16:07:04 +00:00
Commented Oct 28, 2013 at 16:07 — bendataclear
– bendataclear, Commented Oct 28, 2013 at 16:07

Tim Schmelter · Accepted Answer · 2013-10-28 15:55:07Z

5

You have declared but not initialized the string array.

You could use LINQ:

Dim charsAsStringArray = inputexpression.
    Select(Function(c) c.ToString()).
    ToArray()

Here's the non-linq way:

Dim strArray(inputexpression.Length - 1) As String
For i = 0 To charArray.Length - 1
    strArray(i) = inputexpression(i).ToString()
Next

edited Oct 28, 2013 at 15:55

answered Oct 28, 2013 at 14:58

Tim Schmelter

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4 Comments

igrimpe Over a year ago

What's the need for the first line? inputexpression(index) should be sufficient?

Tim Schmelter Over a year ago

What first line? The first code snippet has just one line and the second("non-Linq") has this first line: Dim charArray = inputexpression.ToCharArray().

igrimpe Over a year ago

Dim charArray = inputexpression.ToCharArray() but also Dim charsAsStringArray = inputexpression.ToCharArray(). Why do you use .ToCharArray if you could simply use inputexpression.Select() because the String is already treated as Array of Char then?

Tim Schmelter Over a year ago

@igrimpe: good point, edited my answer. That was just a copy-paste issue. Thanks.

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