Reading data from an online text file...

[_Cobra]

What I want to do in a program is read data from a text file. I've got some code that works fine for text files in the solution's folder:

try{
StreamReader^theReader = gcnew StreamReader("file.txt");
}
catch(FileNotFoundException^a){
MessageBox::Show("File Not Found Exception:\r\n" + g, "Alert", MessageBoxButtons::OK);
}
catch(ArgumentException^b){
MessageBox::Show("Argument Exception:\r\n" + f, "Alert", MessageBoxButtons::OK);
}


What if I wanted to read the data in from an online text file? I tried to replace file.txt with the URL of the text file but got the argument exception error.
Am I going at this the wrong way?

Please, go easy on the C++ jargon in any replies. I'm quite new to this.

[zerver]

That looks like C#, you have come to the wrong forum

You can have a look at URLDownloadToFile

http://msdn2.microsoft.com/en-gb/library/ms775123.aspx

[Marc G]

[ moved thread ]

[_Cobra]

That looks like C#, you have come to the wrong forum

You can have a look at URLDownloadToFile

http://msdn2.microsoft.com/en-gb/library/ms775123.aspx

I tried the code from the page you linked me to, but I'm getting an error when I tried using it in my program.

//*****WEBPAGE'S CODE:
HRESULT URLDownloadToFile( LPUNKNOWN pCaller,
LPCTSTR szURL,
LPCTSTR szFileName,
DWORD dwReserved,
LPBINDSTATUSCALLBACK lpfnCB
);
//*****MY CODE:
HRESULT URLDownloadToFile(
NULL,
"http://www.my_webpage.com/filename.txt",
"filename.txt",
0,
NULL);

Did I format this correctly? Whenever I debug, I get an error that I have too many initializers. Any ideas?

While I'm at it, do I have to download this file before I use it in my program? Is there a way to read data in directly from it?

Thanks guys,
-David

[Marc G]

You should be calling it like this:
HRESULT hRes = URLDownloadToFile(
NULL,
"http://www.my_webpage.com/filename.txt",
"filename.txt",
0,
NULL);

[_Cobra]

I tried that but I'm still getting an error on the last line:
error C2664: 'URLDownloadToFileW' : cannot convert parameter 2 from 'const char [39]' to 'LPCWSTR'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

[Zaccheus]

If you are writing this in C++/CLI, would it not be better to use System::Net::WebClient::DownloadFile (http://msdn2.microsoft.com/en-us/library/system.net.webclient.downloadfile.aspx) ?


System::Net::WebClient^ webClient = gcnew System::Net::WebClient();
webClient->DownloadFile("http://www.foo.com/bar.txt", "C:\\foo\\bar.txt");

:)

[Marc G]

If you are using C++/CLI, then use Zaccheus solution.

Otherwise, add an L before your strings or put them around _T(), like L"http:..." or _T("http:...")

[giddy_guitarist]

Hi ,

i have the exact same problem ,i'm making a simple program called message(its just a silly program).... should download a message from a .txt file on a URL and display it to the user after a given time.

I'm using PURE C , and win32 API (no C++) and i have vs.net 2005. I went to Project Menu ->Properties -> Configuration Properties|Linker| General and added "D:\Microsoft Visual Studio 8\VC\PlatformSDK\Lib" to Additional Library Directories

i also have
#include <urlmon.h>

i use the URLdownload API in a function like so:
void GetSettings()
{
char temp[2];
URLDownloadToFile(0,"<URL>","C:\\temp.txt" , 0,0);
FILE *fp;
fp = fopen(TMP_PATH ,"r");
fgets(the_message , 200 , fp);
fgets(temp , 2 , fp);
show_at = atoi(temp);
fclose(fp);
}

and the 2 errors i get even after doing the above is:
Error 4 error LNK2019: unresolved external symbol _URLDownloadToFileA@20 referenced in function "void __cdecl GetSettings(void)" (?GetSettings@@YAXXZ) main.obj
Error 5 fatal error LNK1120: 1 unresolved externals e:\Gid\My Creations\Message Prank\Debug\message.exe 1


i also get 2 deprecated warnings for fopen and srcat ..and 1 :
Warning 3 warning LNK4076: invalid incremental status file '.\Debug/message.ilk'; linking nonincrementally message

also , dont know if its worth mentioning , if i hover over URLDownloadToFile() i get a tooltip telling me its defined and could my problem have anything to do with ASCII and unicode.The linker does say: "_URLDownloadToFileA"


Could someone PLEASE HELP!

Gideon

[Marc G]

The error is pretty clear. It is missing the URLDownloadToFile. A quick lookup on MSDN would tell you that you need to link with Urlmon.lib to use this function.

[giddy_guitarist]

ok , i did'nt find anything on msdn but on wikipedia somehow.

The directory has to be specified under Project Menu ->Properties -> Configuration Properties|Linker| General|Additional Lib. Dep.

and then the LIBRARY ITSELF has to be specified at Project Menu ->Properties -> Configuration Properties|Linker|INPUT! | additional dep.

ok so thats solved! but now . . .. . i get :

a debug assertion failed!~!!!!! - fgets.c

this is because the file c:\temp.txt never gets created! . .. URLDownloadTOFile() doesnt! work! ARRRG!

thats how i call it :

void GetSettings()
{
char temp[2];
URLDownloadToFile(0,"http:////gidisrael.googlepages.com//message.txt","c:\\temp.txt", 0,0);
FILE *fp;
fp = fopen("c:\\temp.txt","r");
//if(fp==NULL)........
fgets(the_message , 200 , fp);
fgets(temp , 2 , fp);
show_at = atoi(temp);
fclose(fp);
}

am i missing something somewhere!!!!! =(

plz help!

[giddy_guitarist]

ok , im sorry. . . the URL to the website is http://gids.. . . .no escape slashes and the path to the FILE . .should have double slashes. C:\\temp.txt

Gideon