Const SPI_GETWORKAREA = 48 '定義常量
Private Type RECT '自定義變量結構，rect通常用於確定矩形範圍
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type
Private Declare Function SystemParametersInfo Lib "user32" Alias "SystemParametersInfoA" _
(ByVal uAction As Long, ByVal uParam As Long, lpvParam As Any, _
ByVal fuWinIni As Long) As Long '聲明API
Private Sub Command1_Click() '按鈕壹單擊事件過程
Dim lRet As Long ’變量聲明為長整形
Dim apiRECT As RECT ’聲明變量為自定義結構
lRet = SystemParametersInfo(SPI_GETWORKAREA, vbNull, apiRECT, 0) '調用api將窗口值寫入自定義結構，並返回是否成功。
If lRet Then '返回非零則執行
Label1.Caption = "寬: " & apiRECT.Right - apiRECT.Left & " 高: " & apiRECT.Bottom - apiRECT.Top '成功則寫出到標簽
Else '返回零則失敗
Print "調用 SystemParametersInfo 失敗" '提示失敗
End If
End Sub
Private Sub Command2_Click()
End '退出
End Sub