VBA Mid Function

VBA Mid function is a string manipulation function that allows users to extract a specific number of characters or a portion of a string from a given text based on a starting position and a desired length. It is part of the Microsoft Office suite’s Visual Basic for Applications (VBA) programming language and is commonly used to manipulate and work with text data in Excel macros.

Purpose of VBA Mid Function

The purpose of the Mid function is to extract a substring or a specific portion of a string from a given text. This function is particularly useful for working with large amounts of text data where only a certain portion of the information is needed for analysis or manipulation.

Syntax:

Mid(text, start_num, optional num_chars)

Arguments:

• Text: This is a required argument that refers to the text or string from which the characters will be extracted.
• Start_num: This is a required argument that specifies the starting position of the characters to be extracted.
• Num_chars (optional): This is an optional argument that specifies the number of characters to be extracted from the specified starting position. If this argument is not provided, the function will extract all the characters from the starting position to the end of the text.

Understanding VBA Mid Function

To understand the usage of the Mid function, consider the following example where we have a list of employee names in column A and we want to extract the first three characters from each name and display them in column B.

Sub ExtractNames()
  Dim lastRow As Long
  lastRow = Range("A" & Cells.Rows.Count).End(xlUp).Row
    
  'Loop through each cell in column A
  For i = 1 To lastRow
    'Extract the first three characters using Mid function
    Range("B" & i).Value = Mid(Range("A" & i).Value, 1, 3)
  Next i
End Sub

In this example, the Mid function is being used to extract the first three characters from the string in each cell of column A. The extracted characters are then displayed in column B using the Range.Value property.

Remarks:

• The Mid function can only be used with strings and cannot be used with other data types such as numbers or dates.
• The starting position argument, start_num, can be any numeric value, but if it is a negative value, it will count backwards from the end of the string. For example, a start_num of -3 will start the extraction three characters from the end of the string.
• If the starting position argument, start_num, is greater than the length of the string, the function will return an empty string.
• If the optional num_chars argument is not provided, the function will extract all the characters from the starting position to the end of the string.
• If the optional num_chars argument is provided but its value is greater than the length of the string starting from the specified starting position, the function will extract all the characters from the starting position to the end of the string.

Important Notes:

• When using the Mid function, it is important to ensure that the desired starting position and number of characters to be extracted are correct to avoid any errors or incorrect data manipulation.
• The Mid function can also be used with other VBA string manipulation functions such as ‘Left’ and ‘Right’ to perform more complex tasks with text data.

The VBA Mid function is a useful tool for working with text data in Excel macros. It allows users to easily extract a specific number of characters or a portion of a string from a given text based on a starting position and a desired length. By understanding its syntax, arguments, example, remarks, and important notes, users can effectively use this function in their VBA projects to manipulate text data.

VBA Mid Function with Examples

Example 1: Basic Syntax of Using Mid Function

The Mid function is a built-in function in VBA that is used to extract a string from a larger string based on a specified starting position and length. It is particularly useful for manipulating strings in VBA codes.

Dim originalString As String
Dim extractedString As String
originalString = "Hello, World!"
extractedString = Mid(originalString, 7, 5)
MsgBox extractedString

Output: World

1. In this example, we declared two string variables – originalString and extractedString.
2. originalString is assigned with “Hello, World!”.
3. The Mid function is then used to extract a substring from originalString, starting at the 7th character and with a length of 5 characters.
4. The extractedString variable holds the output of the Mid function.
5. The output of extractedString is then displayed using the MsgBox function, which will show “World”.

This example shows the basic syntax of using the Mid function. The first argument is the string from which the substring will be extracted, the second argument is the starting position of the substring, and the third argument is the number of characters to be extracted.

Example 2: Using Mid Function to Replace Characters

The Mid function can also be used to replace characters in a string. This is often used to clean up data or to perform data validation.

Dim originalString As String
Dim replacedString As String
originalString = "Hello, World!"
replacedString = Mid(originalString, 1, 7) & "VBA"
MsgBox replacedString

Output: Hello, VBA!

1. In this example, we have a string “Hello, World!” which we want to replace the last two characters with “VBA”.
2. We use the Mid function to extract the first 7 characters of the original string, which are “Hello, “.
3. We then concatenate the extracted string with “VBA” using the “&” symbol.
4. The output of replacedString is then displayed using the MsgBox function, which will show “Hello, VBA!”.

Here, the Mid function is used not only to extract a substring but also to replace characters in a string. This is achieved by extracting the first part of the original string and concatenating it with the replacement string.

Example 3: Dynamic Length in Mid Function

One of the advantages of the Mid function is that it allows the length of the extracted substring to be dynamic. This means that the length can be determined at runtime, making the code more flexible.

Dim originalString As String
Dim extractedString As String
Dim length As Integer
originalString = "Hello, World!"
length = Len(originalString)
extractedString = Mid(originalString, 7, length - 7)
MsgBox extractedString

Output: , World!

1. In this example, we want to extract everything after the 7th character in the original string.
2. Instead of manually specifying the length, the Len function is used to determine the total length of the string.
3. The length variable is set to the total length of the original string.
4. The extractedString variable uses the Mid function to extract the substring starting at the 7th character, with a dynamic length that is calculated by subtracting 7 from the total length of the string.
5. The output of extractedString is then displayed using the MsgBox function, which will show “, World!”.

This example shows how the length of the extracted substring can be dynamically calculated, making the code more efficient and less prone to errors.

Example 4: Using Mid Function to Extract Multiple Substrings

The Mid function can be used to extract multiple substrings from a string. This can be achieved by using a loop and manipulating the starting position and length of the extracted substring.

Dim originalString As String
Dim extractedString As String
Dim i As Integer
originalString = "Hello, World!"
For i = 1 To 2
    extractedString = Mid(originalString, i, 5)
    MsgBox extractedString
Next i

Output: Hello
ello,

1. In this example, we want to extract two substrings from the original string using a loop.
2. The For loop is used to iterate through the string, with a variable i that acts as the starting position of the extracted substring.
3. The extractedString variable uses the Mid function to extract a substring of length 5, starting at the position specified by the i variable.
4. The output of extractedString is then displayed using the MsgBox function, showing the first and second substring respectively.

This example demonstrates how the Mid function can be used in a loop to extract multiple substrings from a string.

Example 5: Using Mid Function to Extract Text Between Two Keywords

The Mid function can be used to extract text between two keywords in a string. This can be useful when dealing with text that follows a certain format or structure.

Dim originalString As String
Dim extractedString As String
Dim keyword1 As String, keyword2 As String
Dim startPos As Integer, endPos As Integer
originalString = "The quick brown fox jumps over the lazy dog."
keyword1 = "quick"
keyword2 = "dog."
startPos = InStr(originalString, keyword1) + Len(keyword1) + 1
endPos = InStr(originalString, keyword2) - 1
extractedString = Mid(originalString, startPos, endPos - startPos + 1)
MsgBox extractedString

Output: brown fox jumps over the lazy

• In this example, we have a string that follows a specific format – keyword1 followed by the text we want to extract, and then keyword2.
• The InStr function is used to determine the position of keyword1 and keyword2 in the original string.
• The startPos variable is set to the position of keyword1, plus the length of keyword1, and an extra character to account for the spacing.
• The endPos variable is set to the position of keyword2, minus 1 to exclude the period at the end.
• The extractedString variable uses the Mid function to extract the substring starting at the startPos and ending at the endPos.
• The output of extractedString is then displayed using the MsgBox function, showing the text between the two keywords.

This example showcases the importance of using the InStr function to determine the position of specific keywords in a string, which is then used in the Mid function to extract the desired substring.

Conclusion

The Mid function is a powerful tool for manipulating strings in VBA codes. It can be used to extract, replace, and manipulate characters and substrings in a string. Its ability to have dynamic length and its usage in loops make it a versatile function that is essential in many VBA projects.

These examples provide a basic understanding of the Mid function and how it can be used in different scenarios. With practice, one can master the usage of the Mid function and enhance their VBA coding skills.