Discovering Visual Basic .NET: Using Functions and Arguments
With the Space function, you can easily create a string with lots of spaces in it. Just send a number indicating how many spaces you want, and Space returns a string of that length, filled with spaces:
This function returns " " (15 spaces).
Left, Mid, Right
Left takes two arguments: a string and a number. It returns a string that consists of the left-most characters of the string sent:
This function returns "Dog".
This function returns "Rubb".
Right works exactly the same way, but it takes the characters from the right side of the string:
This function returns "bones".
Mid takes characters from anywhere within a string. The first argument is the string you want to work with. The second argument determines where in the string to begin, and the third argument determines how many characters to use. Mid returns the string that results:
Mid("Quick brown fox",7, 5)
This function returns "brown".
It starts with the seventh character ("b") and takes five characters total (including the seventh).
InStr is a really handy function. It searches for a shorter string within a long string. If it finds the shorter string, InStr returns the position within the larger string where the shorter string can be found.
In other words, InStr returns the character position at which it finds the second argument within the first argument.
Here's an example:
Imports System Imports Microsoft.VisualBasic Module EggsHam Public Sub Main() Dim BigString, FindString As String Dim Position As Integer BigString = "I do not like green eggs and ham." FindString = "eggs" Position = InStr(BigString, FindString) Console.WriteLine("This string: " & FindString) Console.WriteLine("Appears inside: " & BigString) Console.WriteLine("At position " & Position) End Sub End Module
Position holds the value 21, because "eggs" starts at the 21st position in BigString.
Replace goes a step further than InStr. It looks for a small string inside a larger one, and when the small string is found, it is replaced with another specified string.
Here's an example:
Imports System Imports Microsoft.VisualBasic Module MaryLamb Public Sub Main() Dim BigString as string BigString = "Mary had a little lamb" Console.WriteLine(Replace(BigString, "little", "big")) End Sub End Module
This program displays the following line:
Mary had a big lamb
Format enables you to take a date, time, or number and format it the way you want it to look. You send two arguments. The first can be a date, a time, or a number. Or, you can use a variable holding a date, time, or number. The second argument can hold many different values depending on what you're trying to format and how you want it to look.
Here's an example:
Imports System Imports Microsoft.VisualBasic Module VariousFormats Public Sub Main() Console.WriteLine(Format(0.675,"p")) Console.WriteLine(Format(55102,"n")) Console.WriteLine(Format(1552,"c")) Console.WriteLine("") Console.WriteLine(Format(Now,"g")) Console.WriteLine(Format(Now,"d")) Console.WriteLine(Format(Now,"t")) Console.WriteLine("") Console.WriteLine(Format(Now,"MMM dd, yyyy")) End Sub End Module
Here's the result this program produces:
67.50 % 55,102.00 $1,552.00 12/21/2004 6:20 PM 12/21/2004 6:20 PM Dec 21, 2004
As this example shows, you can use many letters for the second argument, and each letter has a predefined meaning. Table 1 lists common examples of the letters you can use for this argument.
Table 1. Common Format arguments.
|Letter||What It Means|
You also can enter your own format using certain letters in combination, as the last Format line in the example shows. For more details and options, see the .NET Framework documentation.
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