Re: How Can i Call a Function Providing its name as a string - C / C++ / MFC Discussion Boards

Christopher Duncan6-Sep-06 7:52

6-Sep-06 7:52

Hey, Rick.

I've got some MCI code in an app at the house and I'll be happy to look at it to see if I've fought that battle already. It's been awhile, and I've slept since then. Big Grin | :-D

The tricky part will be remembering to take a look. Send me an email from this post to remind me, and I'll poke around and see if I can help. I seem to recall that you can enumerate the devices. If so, I'll shoot you some code.

Author of
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www.PracticalStrategyConsulting.com

storing data to a file

vijay_aroli6-Sep-06 1:53

vijay_aroli

6-Sep-06 1:53

hello. i am writing certain data from memory into file on the disk. how can i write the same data into a file on the FTP server??? is the process of writing data to an FTP file is same as that of writing data on to file in the local disk??

vijay

Re: storing data to a file

led mike6-Sep-06 6:07

led mike

6-Sep-06 6:07

http://en.wikipedia.org/wiki/File_Transfer_Protocol[^] Roll eyes | :rolleyes:

"Alot of the people on this forum are incredibly stupid, thinking that the internet is real"
Score: 1.0 in the Soap Box

led mike

Re: storing data to a file

Jun Du6-Sep-06 10:32

Jun Du

6-Sep-06 10:32

There is no such a thing called "FTP file". FTP is a protocol, which is used to transfer data in two formats: ASCII and binary.

Maybe you can clearify a bit about what you wanted? If you write data to the FTP server, which is mapped as mapped network drives on your local machine, then the write is just as you're writing to a local drive.

Best,
Jun

How Can i Call a Function Providing its name as a string

MIAN KAMRAN6-Sep-06 1:29

MIAN KAMRAN

6-Sep-06 1:29

How Can i Call a Function Providing its name as a string in C\C++

Re: How Can i Call a Function Providing its name as a string

Rajesh R Subramanian6-Sep-06 1:36

Rajesh R Subramanian

6-Sep-06 1:36

Name as a string? Can you be more specific? I do not get this question.

Brahmma

According to the laws of aerodynamics, the bumble bee must not be able to fly. The bumble bee does not know aerodynamics. It goes on flying anyway.

Re: How Can i Call a Function Providing its name as a string

Cedric Moonen6-Sep-06 1:38

Cedric Moonen

6-Sep-06 1:38

Simple answer: you can't.

But, why would like to do such a thing ? Provide as much relevant information you can so we can help you to find a better solution (it probably results from a bad design).

Cédric Moonen
Software developer

Charting control [Updated - v1.1]

Re: How Can i Call a Function Providing its name as a string

Frank K6-Sep-06 2:44

Frank K

6-Sep-06 2:44

Hi,

Function as a string?? Why? ... but ...

You can get the address of a function with

<br />
FARPROC GetProcAddress(HMODULE hModule, LPCSTR lpProcName);<br />

You need the module handle and the name of the function.

Example for the function GetMenu from user32.dll

<br />
typedef HMENU (WINAPI *GETMENU) (HWND);<br />
GETMENU FuncGetMenu;<br />
HMODULE hUser32Dll;<br />
<br />
_hUser32Dll = ::LoadLibrary("user32.dll");<br />
if(NULL != hUser32Dll)<br />
{<br />
FuncGetMenu = (GETMENU)::GetProcAddress(hUser32Dll, "GetMenu");<br />
}<br />
<br />
if(NULL != FuncGetMenu)<br />
{<br />
FuncGetMenu(WindowHandle); //HMENU GetMenu(HWND hWnd);<br />
}<br />

This is an example for dynamic load a dll.
--> You need more than only the function name! You also need the function declaration.

HTH
Frank

Re: How Can i Call a Function Providing its name as a string

C^hris L^osinger6-Sep-06 2:54

C^hris L^osinger

6-Sep-06 2:54

you can't, not directly anyway.

but, you could create a map that maps strings (names) to function pointers.

image processing | blogging

Re: How Can i Call a Function Providing its name as a string

Viorel.6-Sep-06 3:12

Viorel.

6-Sep-06 3:12

The next sample for Visual Studio 2005 uses map and function pointers:

#include "stdafx.h"
#include "math.h"
#include <map>
#include <string>

void main()
{
	using namespace std;

	typedef double (* FUNCTION_POINTER)(double);

	// make the map

	map< string, FUNCTION_POINTER > functions;

	functions["sin"] = sin;
	functions["cos"] = cos;
	functions["tg"] = tan;

	// test: call a function by name

	std::string name;

	name = "cos";

	FUNCTION_POINTER function = functions[name];

	double result = function(1.2);

}

I hope it works and gives you some ideas.

Re: How Can i Call a Function Providing its name as a string

yjzh6-Sep-06 4:20

yjzh

6-Sep-06 4:20

a piece of cake, function pointer or functors can do this.

boost

Re: How Can i Call a Function Providing its name as a string

Rilhas8-Sep-06 9:29

Rilhas

8-Sep-06 9:29

Complementing to the other answers already given, the quick answer would be no, at least not in the way BASIC (for example) lets you do it (something like execute("a=myfunc(10,20)").

The process of calling functions based on the contents of a string has to be manually coded in some way. The most "automatic" way is the already mentioned "GetProcAddress" (you can hide most of the steps required inside macros or in a general purpose function), but prototypes will be always a pain (unless if they are, trivially, the same).

Depending on the extent of work you are willing to do, you can go as far as building your own C/C++ interpreter. I did this once, for a home automation system, where I made a program to go through all of my header files, scan function names and prototypes, and write code to execute the correct function with the correct parameters based on the contents of a string (the command entered by the user). Is not very hard work if you control the classes and functions. If not then be prepared for trouble.

I hope this helps,
Rilhas

Winsock TCP Client disconnect

Eytukan6-Sep-06 1:21

Eytukan

6-Sep-06 1:21

I have a question.
Are these same?

1. Close the client application window. [ Closes the stream ],
(Server gets out of the below block)

<br />
do<br />
{<br />
n=recv(client,buff,MAX_BUFF_SIZE,0);<br />
 if(n==SOCKET_ERROR )	<br />
  {<br />
   break;<br />
  }<br />
}while()<br />

2. UnPlug the client's network cable. [should close the stream?] ,
server never gets notified? it never happens. WTF??? WTF | :WTF:

I'm not able to detect the latter one. Please help. If the n/w cable is unplugged, the stream would be broken and it should fire a sock exception right? Unsure | :~

<marquee scrollamount="1" scrolldelay="1" direction="up" height="10" step="1">--[ Jig | [Dance]

]--

[My Current Status]

Link2006 wrote:Let's take it outside of CP
Jeremy : Please don't.I would love to see this.I'm making the popcorn already.

Re: Winsock TCP Client disconnect

Frank K6-Sep-06 2:29

Frank K

6-Sep-06 2:29

Hi,

the value from SOCKET_ERROR is -1
if you unplug the network recv will be return 0

Change your code to

<br />
do<br />
{<br />
n=recv(client,buff,MAX_BUFF_SIZE,0);<br />
if(1 > n)<br />
{<br />
break;<br />
}<br />
}while();<br />

HTH
Frank

Re: Winsock TCP Client disconnect

Eytukan6-Sep-06 3:17

Eytukan

6-Sep-06 3:17

Nope!

It doesn't work. The disconnection is not detected. Please help.

<marquee scrollamount="1" scrolldelay="1" direction="up" height="10" step="1">--[ Jig | [Dance]

]--

[My Current Status]

Link2006 wrote:Let's take it outside of CP
Jeremy : Please don't.I would love to see this.I'm making the popcorn already.

Re: Winsock TCP Client disconnect

cmk6-Sep-06 20:35

cmk

6-Sep-06 20:35

TCP does _not_ maintain a connection, it only maintains information about the connection.

Unplugging the cable merely prevents data from moving.

You need to implement a ping or timeout type feature in your protocol if you want to be notified if/when the cable is unplugged.

See:
http://tangentsoft.net/wskfaq/newbie.html#abnormalclose[^]

...cmk

Save the whales - collect the whole set

Re: Winsock TCP Client disconnect

Eytukan7-Sep-06 21:09

Eytukan

7-Sep-06 21:09

Thanks for the link!! I just stopped tussling with the issue. Implementing a sensor now Wink | ;)

<marquee scrollamount="1" scrolldelay="1" direction="up" height="10" step="1">--[ Jig | [Dance]

]--

[My Current Status]

Link2006 wrote:Let's take it outside of CP
Jeremy : Please don't.I would love to see this.I'm making the popcorn already.

Data Type Conversion Problem

Programm3r6-Sep-06 0:47

Programm3r

6-Sep-06 0:47

Hi all,

I'm struggling with the following:

I have these two pointer:
<code>char* username = "value1";
char* servername = "value2";</code>

And these other two pointers:
<code>
unsigned short* uni_domain;
unsigned short* uni_username;
</code>

And I'm trying to assign the fisrt two pointer values to the second two pointer, I tried the following:

<code>
uni_domain = (LPWSTR)username;
uni_username = (LPWSTR)servername;
</code>

But the function : <code>NetUserGetInfo</code> is not equal to <code>NERR_Success</code>, which indicates its not valid.

When I do this it works:
<code>
uni_domain = L"value1";
uni_username = L"value2";
</code>

But I'm sending values to a function, and the above will not help my cause.

Can anyone help me?

Only programmers that are better than C programmers are those who code in 1's and 0's..... Smile | :)

Programm3r

Re: Data Type Conversion Problem

Waldermort6-Sep-06 0:58

Waldermort

6-Sep-06 0:58

You can't typcast a unicode string to an ansi string, you must use the MultiByteToWideChar() function, or the W2A macro. I think you would be better off reading about the TCHAR strings and the _T() macro, it's a lot easier to deal with.

how to dermine weather the Given string is numeric or not , vc++

cybersadhu6-Sep-06 0:34

cybersadhu

6-Sep-06 0:34

hi everyone,

i have to know that the given CString variable contains numeric value , eg
CString str = "1233.23" , is having a numeric value, i want to trap that.

but problem is that i dont know how to determine that the string variable contain the numeric value. ( not like str ="123hh" or str ="hh1234")

Can any body help me

Re: how to dermine weather the Given string is numeric or not , vc++

toxcct6-Sep-06 0:36

toxcct

6-Sep-06 0:36

iterate through each character. it must contain only 0~9, +, -, .

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: how to dermine weather the Given string is numeric or not , vc++

Waldermort6-Sep-06 0:39

Waldermort

6-Sep-06 0:39

If your strings will always start with a numeric value you can use the atoi() function, but from your example I guess not. You would have to go through each character and text the value.

Re: how to dermine weather the Given string is numeric or not , vc++

Hamid_RT6-Sep-06 0:52

Hamid_RT

6-Sep-06 0:52

How to get your string?from a editbox...?its for only number or string?

WhiteSky

Re: how to dermine weather the Given string is numeric or not , vc++

David Crow6-Sep-06 4:04

David Crow

6-Sep-06 4:04

Use isdigit().

"Talent without discipline is like an octopus on roller skates. There's plenty of movement, but you never know if it's going to be forward, backwards, or sideways." - H. Jackson Brown, Jr.

"Judge not by the eye but by the heart." - Native American Proverb

Re: how to dermine weather the Given string is numeric or not , vc++

toxcct6-Sep-06 4:53

toxcct

6-Sep-06 4:53

-3.2 is a valid numeric number ; BTW, - and . characters won't be validate by isdigit() though

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

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