Enhancing String Manipulation in VBA: A Detailed Guide to the One-Dimensional Array Module

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Introduction

In Microsoft Office applications that support VBA (Visual Basic for Applications), developers often find themselves in need of manipulating strings. While VBA has a native Split method, it falls short when it comes to splitting the characters of a single word. This article presents a VBA code module that enables users to load strings into one-dimensional arrays, one character per element, and to join such array characters into single strings again.

Why Use the One-Dimensional Array Module

The one-dimensional array module is particularly useful when working with single words. By allowing users to load strings into one-dimensional arrays, it becomes possible to perform more advanced string manipulation tasks, such as modifying individual characters or analyzing character patterns. Furthermore, this module provides an easy way to join array characters back into single strings, making it an essential tool for any VBA developer.

Getting Started

To get started, copy all of the procedures provided below into a VBA standard module. Save the workbook as an xlsm type, and then run the top procedure to demonstrate the accuracy of the process. The module includes the following key procedures:

1. testStrTo1DArr: A test procedure that verifies the functionality of the StrTo1DArr and Arr1DToStr functions.
2. StrTo1DArr: A function that loads a given input string into a one-dimensional array, with one character per element.
3. Arr1DToStr: A function that takes a one-dimensional array of characters and returns a single string.

Sub testStrTo1DArr()
    ' run this to test array string load
    ' and array to string remake procedures
    
    Dim vR As Variant, vE As Variant
    Dim sStr As String, bOK As Boolean, sOut As String
    
    sStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    
    'split string into array elements
    bOK = StrTo1DArr(sStr, vR, False)
    
    If bOK = True Then
        'optional array transfer
        vE = vR
        
        'remake string from array
        sOut = Arr1DToStr(vE)
        
        'show that output = input
        MsgBox sStr & vbCrLf & sOut
    Else
        Exit Sub
    End If

End Sub

Function StrTo1DArr(ByVal sIn As String, vRet As Variant, _
                    Optional ByVal bLB1 As Boolean = True) As Boolean
    ' Loads string characters into 1D array (vRet). One per element.
    ' Optional choice of lower bound. bLB1 = True for one-based (default),
    ' else bLB1 = False for zero-based. vRet dimensioned in proc.

    Dim nC As Long, sT As String
    Dim LB As Long, UB As Long
    
    If sIn = "" Then
        MsgBox "Empty string - closing"
        Exit Function
    End If
    
    'allocate array for chosen lower bound
    If bLB1 = True Then
        ReDim vRet(1 To Len(sIn))
    Else
        ReDim vRet(0 To Len(sIn) - 1)
    End If
    LB = LBound(vRet): UB = UBound(vRet)

    'load charas of string into array
    For nC = LB To UB
        If bLB1 = True Then
            sT = Mid$(sIn, nC, 1)
        Else
            sT = Mid$(sIn, nC + 1, 1)
        End If
        vRet(nC) = sT
    Next

    StrTo1DArr = True

End Function
    
Function Arr1DToStr(vIn As Variant) As String
    ' Makes a single string from 1D array string elements.
    ' Works for any array bounds.
        
    Dim nC As Long, sT As String, sAccum As String
    Dim LB As Long, UB As Long
    
    LB = LBound(vIn): UB = UBound(vIn)

    'join characters of array into string
    For nC = LB To UB
        sT = vIn(nC)
        sAccum = sAccum & sT
    Next

    Arr1DToStr = sAccum

End Function

Understanding the Code

The testStrTo1DArr procedure is designed to test the functionality of the StrTo1DArr and Arr1DToStr functions. It begins by declaring necessary variables, such as a string containing alphanumeric characters, an array to hold the characters, and a boolean flag to check the success of the StrTo1DArr function.

The StrTo1DArr function takes three parameters: the input string (sIn), the output array (vRet), and an optional boolean value (bLB1) that determines whether the array's lower bound should be one-based (default) or zero-based. The function checks whether the input string is empty, and if not, it initializes the output array based on the selected lower bound. Next, it iterates through the characters of the input string and adds them to the output array.

The Arr1DToStr function takes a one-dimensional array of characters (vIn) and concatenates them into a single string. It first determines the lower and upper bounds of the input array and then iterates through the array elements, joining them into the output string.

Using the Module

To use this module, simply call the StrTo1DArr function to load a string into a one-dimensional array and the Arr1DToStr function to join the array characters back into a single string. The testStrTo1DArr procedure is included to demonstrate the accuracy of the process.

Conclusion

The one-dimensional array module presented in this article is a powerful tool for VBA developers working with Microsoft Office applications. It provides an easy and efficient way to split and reassemble strings, allowing for more advanced string manipulation tasks. By integrating this module into your VBA projects, you can enhance your string manipulation capabilities and create more sophisticated solutions.