Vba api

[pong]

My teacher has written a code for me to download things from yahoo.com
The class has already ended. I found sth I really have no idea and see if somebody explains to me.( I am just a beginning programmer at EXCEL marco. Besides, I dont have much knowledge about computer science )

Private Declare Function URLDownloadToFile Lib "urlmon" Alias "URLDownloadToFileA" _
                                                (ByVal pCaller As Long, _
                                                 ByVal szURL As String, _
                                                 ByVal szFileName As String, _
                                                 ByVal dwReserved As Long, _
                                                 ByVal lpfnCB As Long) As Long

Private Declare Function DeleteUrlCacheEntry Lib "Wininet.dll" Alias "DeleteUrlCacheEntryA" (ByVal lpszUrlName As String) As Long
   
Private Const ERROR_SUCCESS As Long = 0
Private Const BINDF_GETNEWESTVERSION As Long = &H10
Private Const INTERNET_FLAG_RELOAD As Long = &H80000000

From what I have learned from google, I understand urldownloadtofile is a function of urlmon.dll .That sub is the call the api to work.

But what i dont know are as follows
What is Alias and "URLDownloadToFileA" ?

what is pCaller

What is szURL

What is szFileName

WHat is dwReserved?

Private Declare Function DeleteUrlCacheEntry Lib "Wininet.dll" Alias "DeleteUrlCacheEntryA" (ByVal lpszUrlName As String) As Long
   
Private Const ERROR_SUCCESS As Long = 0
Private Const BINDF_GETNEWESTVERSION As Long = &H10
Private Const INTERNET_FLAG_RELOAD As Long = &H80000000

Also what are the functions of these codes ?

Thanks a lot

 

[bensonsearch]

Hi,
The byVal's are variables which the API will use to perform its function.
for eg: szFileName would store the name of the file that is to be downloaded.

Private Const ERROR_SUCCESS As Long = 0
Private Const BINDF_GETNEWESTVERSION As Long = &H10
Private Const INTERNET_FLAG_RELOAD As Long = &H80000000

the above are constants. they store a constant value for the API to use.

the differance is the constants dont change where the variables (byval) can change.

hope this helps