Add common file selection and CSV reading functions

vba_code_common.txt

@@ -64,3 +64,49 @@ Sub ClearDataRows(ByVal ws As Worksheet, ByVal startRow As Long, ByVal columnNum
         ws.Range(ws.Cells(startRow, 1), ws.Cells(lastRow, 20)).ClearContents
     End If
 End Sub
+
+' ============================================================
+' File Dialog - Select CSV file
+' Returns: file path or "" if cancelled
+' ============================================================
+Function SelectCSVFile() As String
+    Dim fileDialog As FileDialog
+    Set fileDialog = Application.FileDialog(msoFileDialogFilePicker)
+    
+    With fileDialog
+        .Filters.Clear
+        .Filters.Add "CSV Files", "*.csv"
+        .AllowMultiSelect = False
+        If .Show <> -1 Then
+            SelectCSVFile = ""
+            Exit Function
+        End If
+        SelectCSVFile = .SelectedItems(1)
+    End With
+End Function
+
+' ============================================================
+' Read CSV file with Shift-JIS encoding
+' Returns: array of lines
+' ============================================================
+Function ReadCSVFile(ByVal filePath As String) As Variant
+    If filePath = "" Then
+        ReadCSVFile = Array()
+        Exit Function
+    End If
+    
+    Dim stream As Object
+    Dim textContent As String
+    
+    Set stream = CreateObject("ADODB.Stream")
+    With stream
+        .Type = 2
+        .Charset = "shift_jis"
+        .Open
+        .LoadFromFile filePath
+        textContent = .ReadText
+        .Close
+    End With
+    
+    ReadCSVFile = Split(textContent, vbLf)
+End Function