This section provides an overview of what vba is, and why a developer might want to use it.

It should also mention any large subjects within vba, and link out to the related topics. Since the Documentation for vba is new, you may need to create initial versions of those related topics.

Recursion allows for repeated, self-referencing calls of a procedure.

The assignment of string-literals in VBA is confined by the limitations of the IDE and the codepage of the current user's language settings. The examples above demonstrate the special-cases of escaped strings, special, non-printable strings and long string-literals.

When assigning string-literals that contain characters that are specific to a certain codepage, you may need to consider internationalization concerns by assigning a string from a separate unicode resource file.

VBA will implicitly convert some types to string as necessary and without any extra work on the part of the programmer, but VBA also provides a number of explicit string conversion functions, and you can also write your own.

Three of the most frequently used functions are CStr, Format and StrConv.

When you need to check for the presence or position of a substring within a string, VBA offers the InStr and InStrRev functions that return the character position of the substring in the string, if it is present.

VBA has built-in functions for extracting specific parts of strings, including:

• Left/Left$
• Right/Right$
• Mid/Mid$
• Trim/Trim$

To avoid implicit type conversion onverhead (and therefore for better performance), use the $-suffixed version of the function when a string variable is passed to the function, and/or if the result of the function is assigned to a string variable.

Passing a Null parameter value to a $-suffixed function will raise a runtime error ("invalid use of null") - this is especially relevant for code involving a database.

A string's length can be measured in two ways: The most frequently used measure of length is the number of characters using the Len functions, but VBA can also reveal the number of bytes using LenB functions. A double-byte or Unicode character is more than one byte long.

The examples shown in this topic use early binding for clarity, and require a reference to the Microsoft ActiveX Data Object x.x Library. They can be converted to late binding by replacing the strongly typed references with Object and replacing object creation using New with CreateObject where appropriate.

Strings can be concatenated, or joined together, using one or more concatenation operator &.

String arrays can also be concatenated using the Join function and providing a string (which can be zero-length) to be used between each array element.

There are times you need to assign a string variable with a specific character repeated a specific number of times. VBA provides two main functions for this purpose:

• String/String$
• Space/Space$.

You must add Microsoft Scripting Runtime to the VBA project through the VBE's Tools → References command in order to implement early binding of the Scripting Dictionary object. This library reference is carried with the project; it does not have to be re-referenced when the VBA project is distributed and run on another computer.

It is much easier to control the boundaries of arrays by declaring the boundaries explicitly rather than letting the compiler fall back on an Option Base {0|1} declaration. This can be done like so:

Dim myStringsA(0 To 5) As String '// This has 6 elements (0 - 5)
Dim myStringsB(1 To 5) As String '// This has 5 elements (1 - 5)
Dim myStringsC(6 To 9) As String '// This has 3 elements (6 - 9)

This article will show how to create a complete custom class in VBA. It uses the example of a DateRange object, because a starting and ending date are often passed together to functions.

• An event can only be Public. The modifier is optional because class module members (including events) are implicitly Public by default.

• A WithEvents variable can be Private or Public, but not Friend. The modifier is mandatory because WithEvents isn't a keyword that declares a variable, but a modifier keyword part of the variable declaration syntax. Hence the Dim keyword must be used if an access modifier isn't present.

The Scripting.FileSystemObject is much more robust that the legacy methods in this topic. It should be preferred in almost all cases.

Operators are evaluated in the following order:

• Mathematical operators
• Bitwise operators
• Concatenation operators
• Comparison operators
• Logical operators

Operators with matching precedence are evaluated from left to right. The default order can be overridden by using parentheses ( and ) to group expressions.

METHODS FOR THE CLASS BY MICROSOFT

PROPERTIES OF THE CLASS BY MICROSOFT

NORMAL MODULE

You should un/comment the uFileSize As Double accordingly. I have tested MD5 and SHA1.