shell 打开自动执行

2005-12-17 10:29:59 189 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

为什么梯度的负方向是梯度下降最快的方向文章目录梯度与导数的关系梯度下降算法梯度方向是上升方向一阶泰勒展开式与负梯度梯度与导数的关系梯度方向指向数值增长最快的方向，大小为变化率。通过这个性质也说明梯度是有方向和大小的矢量。通过梯度的定义我们发现，梯度的求解其实就是求函数偏导的问题，而我们高中所学的导数在非严格意义上来说也就是一元的“偏导”。通过这一点我们自然而然地想到梯度应该是导数向更高维数的推广。换句话说，梯度是矢量,而某点的导数是个常量。梯度下降算法如果函数 f(θ)f(\theta )f(θ)是凸函数，那么就可以使用梯度下降算法进行阅读详情

用midia player播放,在VB中建立一个shell语句,如何让它一执行就自动播放,不用按midia player 的播放键?

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为什么梯度反方向是函数值下降最快的方向？面试遇到的问题：刚接触梯度下降这个概念的时候，是在学习机器学习算法的时候，很多训练算法用的就是梯度下降，然后资料和老师们也说朝着梯度的反方向变动，函数值下降最快，但是究其原因的时候，很多人都表达不清楚。所以我整理出自己的理解，从方向导数这个角度把这个结论证明出来，让我们知其然也知其所以然~ 参考在梯度下降法中，为什么梯度的负方向是函数下降最快的方向？为什么梯度反方向是函数值下降最快的方向？进行整... 阅读详情

mmycsh

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mmycsh 2005-12-18

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其实也就也是用shell把播放器打开,再用命令<Ctrl>+P,在播放器执行就行了.
不用太复杂,如何实现?

rainstormmaster 2005-12-18

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//其实也就也是用shell把播放器打开,再用命令<Ctrl>+P,在播放器执行就行了.
不用太复杂,如何实现?

这样：
Option Explicit

Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long

Private Sub Command1_Click()
Dim mhwnd As Long
Dim pid As Long
pid = Shell("e:\Program Files\Windows Media Player\wmplayer.exe", vbNormalFocus)

'查找类名为WMPlayerApp（这个类名是媒体播放器的顶级窗口的类名，这个类名在你的系统中可能是别的值，你用spy++看一下）的窗口，直到找到为止，这种查找的方法比较简单，但可能误中副车
Do While mhwnd = 0
mhwnd = FindWindow("WMPlayerApp", vbNullString)
DoEvents
Loop
SendKeys "^p"
End Sub

IamDeane 2005-12-17

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使用File或者List控件里，将歌曲路径放到里面，然后利用ListIndex和ListCount就可以使用循环播放了

rainstormmaster 2005-12-17

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Option Explicit

Private Type MenuItem
hMenu As Long
wID As Long
wIDType As Long
End Type

Private Const MF_BYCOMMAND = &H0&
Private Const MF_BYPOSITION = &H400&

Private Const MF_ENABLED = &H0&
Private Const MF_GRAYED = &H1&
Private Const MF_DISABLED = &H2&

Private Declare Function GetMenu Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function GetMenuString Lib "user32" Alias "GetMenuStringA" (ByVal hMenu As Long, ByVal wIDItem As Long, ByVal lpString As String, ByVal nMaxCount As Long, ByVal wFlag As Long) As Long
Private Declare Function GetSubMenu Lib "user32" (ByVal hMenu As Long, ByVal nPos As Long) As Long
Private Declare Function GetMenuItemID Lib "user32" (ByVal hMenu As Long, ByVal nPos As Long) As Long
Private Declare Function GetMenuItemCount Lib "user32" (ByVal hMenu As Long) As Long
Private Declare Function EnableMenuItem Lib "user32" (ByVal hMenu As Long, ByVal wIDEnableItem As Long, ByVal wEnable As Long) As Long
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Const WM_COMMAND = &H111
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long

Private Function FindMenuIDByName(ByVal hMenu As Long, ByVal sName As String, mi As MenuItem)
Dim num As Long, i As Long
Dim sub_menu As Long, length As Long
Dim mnu_name As String
Dim cmdID As Long

If hMenu = 0 Then Exit Function
sName = Replace(sName, "&", "")
num = GetMenuItemCount(hMenu)
For i = 0 To num - 1
sub_menu = GetSubMenu(hMenu, i)
mnu_name = Space$(256)
length = GetMenuString(hMenu, i, mnu_name, Len(mnu_name), MF_BYPOSITION)
mnu_name = Left$(mnu_name, length)
mnu_name = Replace(mnu_name, "&", "")
If InStr(1, mnu_name, sName) > 0 Then
cmdID = GetMenuItemID(hMenu, i)
If cmdID = -1 Then 'Item ID
mi.hMenu = hMenu
mi.wID = i
mi.wIDType = MF_BYPOSITION
Else 'Command ID
mi.wID = cmdID
mi.wIDType = MF_BYCOMMAND
End If
Exit For
End If
FindMenuIDByName sub_menu, sName, mi
Next i
End Function

Private Sub Command1_Click()
Dim mhwnd As Long
Dim pid As Long
pid = Shell("e:\Program Files\Windows Media Player\wmplayer.exe")
Dim hMenu As Long, wID As Long
Dim mask As Long, key As Long
Dim mi As MenuItem
'查找类名为WMPlayerApp（这个类名是媒体播放器的顶级窗口的类名，这个类名在你的系统中可能是别的值，你用spy++看一下）的窗口，直到找到为止，这种查找的方法比较简单，但可能误中副车
Do While mhwnd = 0
mhwnd = FindWindow("WMPlayerApp", vbNullString)
DoEvents
Loop
hMenu = GetMenu(mhwnd)
mi.hMenu = hMenu
If hMenu = 0 Then Exit Sub
Dim s As String
s = "播放/暂停"
FindMenuIDByName hMenu, s, mi
'发送菜单命令播放/暂停
SendMessage mhwnd, WM_COMMAND, mi.wID, ByVal 0&

End Sub

mmycsh 2005-12-17

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我的意思是打开播放器时不是只放一首歌,而是把播放器里原有的所有歌都按顺序放出来.
和用手动打开播放器,再按播放键一样.

rainstormmaster 2005-12-17

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Shell "C:\Program Files\Windows Media Player\wmplayer.exe e:\media\1400k.wmv"

或者，试试这样：
Option Explicit
Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long

Private Sub Command1_Click()
ShellExecute Me.hwnd, "play", "e:\media\1400k.wmv", vbNullString, vbNullString, 1

End Sub

hglai 2005-12-17

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shell "c:/midia.exe d:/aa.wma"

答案来自：http://www.play78.com

shell 打开自动执行

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