VB6中的乘法导致溢出异常-如何解决？

Question

在过时的VB6中，我试图计算可用空间和使用磁盘空间：

Declare Function GetDiskFreeSpace Lib "kernel32" Alias "GetDiskFreeSpaceA" (ByVal lpRootPathName As String, lpSectorsPerCluster As Long, lpBytesPerSector As Long, lpNumberOfFreeClusters As Long, lpTtoalNumberOfClusters As Long) As Long

Dim info As DiskInformation
Dim lAnswer As Long
Dim lpRootPathName As String
Dim lpSectorsPerCluster As Long
Dim lpBytesPerSector As Long
Dim lpNumberOfFreeClusters As Long
Dim lpTotalNumberOfClusters As Long
Dim lBytesPerCluster As Long
Dim lNumFreeBytes As Double
Dim dPercentFreeClusters As Double
Dim sString As String

lpRootPathName = "c:\"
lAnswer = GetDiskFreeSpace(lpRootPathName, lpSectorsPerCluster, lpBytesPerSector, lpNumberOfFreeClusters, lpTotalNumberOfClusters)
lBytesPerCluster = lpSectorsPerCluster * lpBytesPerSector

' Throws overflow exception - I guess there were no Terabyte drives when VB6 came around
lNumFreeBytes = lBytesPerCluster * lpNumberOfFreeClusters

  

lBytesPerCluster = 4096 | lpNumberOfFreeClusters = 474304894

我尝试用CLng包装乘法仍然会得到溢出异常。

我该如何解决? lBytesPerCluster * lpNumberOfFreeClusters？

Answer 1

转换为Variant数据类型：

Dim v1, v2, v3 As Variant
v1 = lBytesPerCluster
v2 = lpNumberOfFreeClusters

' this now works:
? v1*v2