VB.NET Strings - CodersLegacy

This article covers VB.NET Strings.

Strings are an important Data type for any language due to their ability to store text. VB.NET offers several functions that can be used on strings to find out more about the information they contain and retrieve data from them. We’ll also discuss some string related techniques in this article.

String Length

VB.NET gives us the Len function which takes a String as it’s parameters and returns the length of that string as an integer value.

Dim s As String
s = "Hello World"

Console.WriteLine(Len(s))

String Iterations

Iterating over a String allows us to print out each character from it individually. Often comes in handy when dealing with string parsing and regex.

Module Module1
    Sub Main()
        Dim s As String
        s = "Hello World"

        For Each x As String In s
            Console.WriteLine(x)
        Next
     
    End Sub
End Module

Trimming a String

The Trim function removes all leading and trailing white spaces in a string and returns the result. Keep in mind that this does not alter the original string but returns a new string instead.

s =  "   Hello World  "

Console.WriteLine(s.Trim())
Console.Read()

Changing the Case

The Function ToLower() returns a copy of a string with all characters converted to lowercase.

s = "Hello World"

Console.WriteLine(s.ToLower())
Console.Read()

hello world

The Function ToUpper() returns a copy of a string with all it’s characters converted to uppercase.

s = "Hello World"

Console.WriteLine(s.ToUpper())
Console.Read()

HELLO WORLD

Join function

The Join function is part of the String Class. You can use it to combine two or more strings together to form a larger string. The Join function’s first parameter is called the delimiter. It defines what character will be used between each String.

Below we explore three different types of delimiters and experiment with more than two strings as well.

Module Module1
    Sub Main()
        Dim a, b As String
        a = "Hello"
        b = "World"

        Console.WriteLine(String.Join("-", a, b))
        Console.WriteLine(String.Join("", a, b))
        Console.WriteLine(String.Join(" ", "Hi", "Every", "One"))

    End Sub
End Module

Hello-World
HelloWorld
Hi Every One

VB.NET String Indexes

Strings in VB.NET have a wide variety of different functions related to their indexes.

The indexOf function is applied on a string, and returns the index of the character(s) you wish to find within that string. Only returns the index of the first character that it encounters. Returns -1 if not found.

Dim s As String = "Hello World"
		
Console.writeline(s.IndexOf('e'))
Console.writeline(s.IndexOf('l'))
Console.writeline(s.IndexOf('a'))

For the character l only the first index is returned, which is at 2. The l at index three was not reached.

1
2
-1

You aren’t restricted to just single characters either. You can insert entire Strings in the indexOf function. Keep in mind however, the index returned will be of the start of the string, or in other words the index of the first character of the string.

Dim s As String = "Hello World"
		
Console.writeline(s.IndexOf("Hello"))
Console.writeline(s.IndexOf("World"))

0
6

The indexOf function allows us to use two parameters, where the first is the string or character we’re looking for and the second is the starting position. By default the starting position is 0.

We’ll use this function creatively to find the location of both l’s in Hello World.

Dim s As String = "Hello World"
Dim pos As Integer
		
Console.WriteLine(s.IndexOf('l'))
pos = s.IndexOf('l')
Console.WriteLine(s.IndexOf('l', pos+1))

First, we found the location of the first l and then did ran the indexOf function again, starting after the location of the first l. pos has the value 2, the location of the first l, so we add one, so that the indexOf function starts from 3.

Finally, we can add a third parameter called count. By default the IndexOf function reads till the end of the String, but count allows us to control how many characters the function reads from it’s starting position.

Dim s As String = "Hello World"

Console.WriteLine(s.IndexOf("l", 4, 2))

Since only two characters were read, from position 4 and 5, the l and index 9 wasn’t reached.

-1

Insert function

The VB.NET insert function is used to insert a string into another String. All it requires is the target index and the string to be inserted.

Module Module1
    Sub Main()
        Dim a, b As String

        a = "Hello World"
        b = "Wonderful "

        Dim result As String = a.Insert(6, b)
        Console.WriteLine(result)

    End Sub
End Module

In the example above we insert the String “Wonderful” into the String “Hello World” at index 6. The result is shown below.

Hello Wonderful World

StartsWith and EndsWith

The startsWith() function is used on a string to see if starts with a specific string or character. Keep in mind that this function can distinguish between Upper and Lower case characters. In some cases, you might find it useful to convert the string to all upper or lower case before using the startsWith() function.

s = "Hello World"

Console.WriteLine(s.StartsWith("H"))
Console.WriteLine(s.StartsWith("Hello"))
Console.WriteLine(s.StartsWith("h"))

True
True
False

The opposite of the startsWith() function, the endsWidth() checks to see if a string ends with a certain character or string.

s = "Hello World"

Console.WriteLine(s.EndsWith("W"))
Console.WriteLine(s.EndsWith("World"))
Console.WriteLine(s.EndsWith("d"))

False
True
True

VB.NET Split

The VB.NET split function takes a string as input and splits the string into smaller strings. The splits occur around points we call the delimiter. By default, the delimiter is set to a white space (" "). This setting causes the string to break around all the white spaces in it.

Module Module1
    Sub Main()
        Dim s As String
        Dim kit() As String

        s = "Welcome to VB.NET Strings"
        kit = Split(s)
        For Each x As String In kit
            Console.WriteLine(x)
        Next

    End Sub
End Module

In the code above, we use the split function with it’s default delimiter. This returns an iterable object to use. We then proceed to iterate over it using a For Each loop, printing out each value one by one. (The variable kit is an Array, due to an array being returned from the Split function).

Welcome
to
VB.NET
Strings

Next we’ll try the delimiter with a different value.

Module Module1
    Sub Main()
        Dim s As String
        Dim kittens() As String

        s = "1#2#3#4#5"
        kittens = Split(s, "#")
        For Each x As String In kittens
            Console.WriteLine(x)
        Next

    End Sub
End Module

This example is pretty self explanatory.

This marks the end of the VB.NET Strings Tutorial. Any suggestions or contributions for CodersLegacy are more than welcome. Any questions about the tutorial content can be directed to the comments section below.