如何统计字符串中vbTab数量？达到3个时添加vbCrLf换行

Hey there! Let's break down how to solve this problem—we need to count the number of vbTab characters in a dynamically built string and insert a vbCrLf every time that count hits 3. Here's a straightforward, flexible approach:

Step 1: Track Tab Count Dynamically #

Instead of building the string blindly and then modifying it later, we'll keep a running count of tabs as we append each message. This is efficient and avoids reprocessing the entire string every time we add content.

Step 2: Count Existing Tabs (If Starting with a Pre-built String) #

If you're starting with an existing string (like your example), first calculate how many tabs are already present so we can pick up where we left off.

Complete Code Example #

' Initialize your starting string (as given in your example)
Dim msg As String = "message 1" & vbTab & " Message 2 " & vbTab & "Message 3" & vbTab

' Function to count existing vbTabs in a string
Private Function CountTabs(inputStr As String) As Integer
    ' Calculate by comparing original length to length with tabs removed
    Return (Len(inputStr) - Len(Replace(inputStr, vbTab, ""))) \ Len(vbTab)
End Function

' Initialize tab count with existing tabs
Dim tabCount As Integer = CountTabs(msg)

' Example: Dynamically append more messages
Dim newMessages() As String = {"Message 4", "Message 5", "Message 6", "Message 7", "Message 8"}

For Each message As String In newMessages
    ' Append the message followed by a tab
    msg &= message & vbTab
    tabCount += 1 ' Increment tab count
    
    ' Check if we've hit 3 tabs (or a multiple of 3)
    If tabCount Mod 3 = 0 Then
        msg &= vbCrLf ' Add newline
    End If
Next

' Output the result
Console.WriteLine(msg)

How This Works #

• Counting Existing Tabs: The CountTabs function uses string replacement to reliably count how many vbTab characters are in the initial string.
• Dynamic Appending: For each new message, we add it to the string along with a vbTab, then increment our tab counter.
• Adding Newlines: Whenever the tab count is a multiple of 3 (using Mod 3 = 0), we append a vbCrLf to create a new line.

Result of the Example #

The final string will look like this (formatted for readability):

message 1	 Message 2 	Message 3	
Message 4	Message 5	Message 6	
Message 7	Message 8	

(Note: \t represents vbTab, \r\n represents vbCrLf)

Alternative: Batch Processing #

If you have a list of messages to add all at once, you can process them in chunks of 3 for cleaner code:

Dim newMessages() As String = {"Message 4", "Message 5", "Message 6", "Message 7", "Message 8"}

For i As Integer = 0 To newMessages.Length - 1 Step 3
    ' Build a chunk of up to 3 messages with tabs
    Dim chunk As String = String.Join(vbTab, newMessages.Skip(i).Take(3)) & vbTab
    msg &= chunk
    
    ' Add newline only if we added a full chunk of 3 messages
    If i + 3 <= newMessages.Length Then
        msg &= vbCrLf
    End If
Next

This approach groups messages into sets of 3, joins them with tabs, and adds a newline after each full group.

内容的提问来源于stack exchange，提问作者Kapil