hex converting

NewHSKid

Hi everyone, First off i would like to say this site is great, especially for a 15 year old that is trying to learn VC++ on his own. I want to send a hex number to the screen, but don't know how. What data type should it be, and how would i represent a hex number. For example I want to send something like 5FF00231 which would be an 4 byte number. I don't know how though, would it be an int, a string? Please help...thank you so much

Brian Delahunty

Do you just want to display "5FF00231" on the screen??? If so just send it as a normal string. Regards, Brian Dela :-) IE 6 required: http://www.briandela.com[^]
It works now.

David Crow

So is your question about converting base X numbers to base 16, or displaying text to the screen? If the former, try: int number = 1609564721; char str[16]; sprintf(str, "%#x", number); If the latter, try: printf("%s\n", str); or cout << str << endl;

NewHSKid

My friends dad gave me a program to write cause he said it will make me learn. I have to connect to a server and send it 4 byte messages that have the form of 5FF00239. The message changes though, because the window (dialog i think its called) has 2 check boxes. If only the first check box is checked then the message should be 5FF00239 and if the second check box is only check it should be 5FF0023A. But if both are checked then he wants the message to be 5FF0023B. How do I make these messages? I don't know what type they should be. I can do everything else he wants except i don't know how to do the message. I thought it would be a string, but he says if it is, then the message is 8 bytes instead of 4? Please help me...

Lost User

Hex numbers are usually preceded by the characters 0x to indicate the following four byte code is a hex value and not an integer. So, the end message should read something like 0x5FF00231. I would use an integer (because hex numbers are generally used to display a 32-bit integer unsigned or signed in Base 16 format - remember that, especially if you want to get into the games industry :)). So my code in WinMain would look like : int WinMain(blah...) { int myhex = 0x5FF00231; char message[32]; sprintf(&message[0], "0x%x", myhex); ::MessageBox(NULL, message, message, MB_OK); } } Hope that helps you :)

Lost User

to be absolutely correct you could use the \0 null terminator to end the string. I always use at least a 32 byte string cos memory byte placements like multiples of 32 :) to avoid memory padding. sprintf(&message[0], "0x%x\0", myhex);

NewHSKid

That is what I want to do later on, I want to program video games. :-) Can you explain what the char message[32]does?

David Crow

Ok, numbers are treated differently when sending them versus displaying them. When you talk about a "hex number," that is for display purposes only. In other words, 1609564729 and 0x5FF00239 are treated identically by the computer. It stores them as binary regardless of how you use them. Now if you are sending "1609564729" and "0x5FF00239" (notice the quotes) to some other process/computer, then they are two totally different things. So, whether you send 1609564729 or 0x5FF00239 to the server, it makes no difference. What mechanism are you using to send data to the server?

NewHSKid

Hi, thanks for helping me. mechanism? I want to use the int send command. Is that what you are talking about. So you are saying that I can use a int variable, but just put 0x in front of the number?

David Crow

It reserves a spot (named "message") in memory for 32 characters.

NewHSKid

but I only need 4 bytes? should i change the 32 to 4 then? Jimmy Just cause I am 15, doesn't mean I'm dumb! (I'll really be 4 on Feb. 29...the year 2004)

David Crow

Bingo!! These three code snippets are the same: int num = 123456789; // base-10 SendToServer(num); int num = 0x75BCD15; // base-16 SendToServer(num); int num = 0726746425; // base-8 SendToServer(num);

David Crow

You don't need this at all. Dangleberry's post was just showing you how to convert a number to a string (which was then displayed in a message box).

NewHSKid

For the send command, i have problems it needs the socket and a message and a length, and some flags. Its says I can't use int because the message has to be const char *. for the length is that in bytes? should it be 4 or 10 to represent all numbers/letters? Jimmy Just cause I am 15, doesn't mean I'm dumb! (I'll really be 4 on Feb. 29...the year 2004)

David Crow

How about a code snippet of what you are trying to do?

NewHSKid

hi, here is what i want to do, the program is connected to the server already. (I don't know how to connect, i just use my friends dad program to connect) int message; message = 0x5FF0023A; send(s, message, strlen(message), 0); It says send can't convert parameter 2 from int to const char * and it says the same thing about strlen. Jimmy Just cause I am 15, doesn't mean I'm dumb! (I'll really be 4 on Feb. 29...the year 2004)

David Crow

NewHSKid wrote: the program is connected to the server already. (I don't know how to connect, i just use my friends dad program to connect) Does that mean he is supplying you with a valid socket descriptor? Given that the second parameter of send() is expecting a char*, you'll need:

int nMessage = 0x5FF0023A;
char szMessage[9]; // hold 8 characters plus a \0
sprintf(szMessage, "%d", nMessage); // or itoa(nMessage, szMessage, 16);
int nBytes = send(s, szMessage, lstrlen(szMessage), 0);

NewHSKid

Hi, Thanks for helping. So when i use that code, the receiving program will get the hex number of 5FF0023A? Jimmy Just cause I am 15, doesn't mean I'm dumb! (I'll really be 4 on Feb. 29...the year 2004)

Lost User

try this : send(s, (const char FAR*)message, sizeof(message), 0); though the sizeof(message) param can just be 0, as message oriented sockets will send a zero-length transport datagram. :cool:

David Crow

No, the recv() function on the other end will receive "5FF0023A" as a char*. It can convert that to an integer (long actually) with strtol(). long lMessage; char szMessage[9], *stop; int nBytes = recv(s, szMessage, sizeof(szMessage), 0); lMessage = strtol(szMessage, &stop, 16);