Excel VBA：如何將字符串作爲指針傳遞給附加字符串的過程？

Question

我想將一個String作爲in/out參數傳遞給一個過程。我知道這不像VBA通常的作品，但這是由於一個特殊情況。我有一個已經存在的代碼生成器工具 - 爲文件格式解析器生成代碼。我不想破解這些代碼。生成的語法可以很容易地轉換爲VBA使用文本替換這沒什麼大不了的（我已經這樣做了）。但是很難將職能轉換爲職能。

我已經知道了我如何通過傳遞指針來擴展字符串。但是我怎樣才能將字符附加到字符串？

Option Explicit 

Private Declare Sub CopyMemory Lib "kernel32" _ 
Alias "RtlMoveMemory" (Destination As Any, Source As Any, _ 
    ByVal length As Long) 

Private Declare Function lstrlenA Lib "kernel32" _ 
    (ByVal lpString As Long) As Long 

Private Declare Function lstrlenW Lib _ 
    "kernel32" (ByVal lpString As Long) As Long 


Sub AppendString(i_pt As Long, i_what As String) 
    Dim strLentgh As Long     ' variable to hold the length of string 
    Dim ptrLengthField As Long    ' pointer to 4-byte length field 

    ' get the length of the string 
    ptrLengthField = i_pt - 4    ' length field is 4 bytes behind 
    CopyMemory strLentgh, ByVal ptrLengthField, 4 

    ' extend the String length 
    strLentgh = strLentgh + (Len(i_what) * 2) 
    CopyMemory ByVal ptrLengthField, strLentgh&, 4 

    ' How to apped the string? 
    ' CopyMemory ByVal i_pt, ???? 
End Sub 

Sub test2() 
    Dim str As String 
    Dim sPtr As Long 

    str = "hello" 
    sPtr = strPtr(str) 

    Debug.Print Len(str) 
    Call AppendString(sPtr, " there") 
    Debug.Print Len(str) 
    Debug.Print str 
End Sub 

Answer 1

VBA可以做到這一點本身

Sub AppendString(byref str as string, i_what As String) 
    str = str & i_what 
end sub 

爲了測試

Sub Test() 
    Dim s As String 

    s = "Hello" 

    AppendString s, " World" 
    Debug.Print s 
End Sub