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Top Forums Programming Simple Network Program Difficulties Post 17665 by AtleRamsli on Tuesday 19th of March 2002 05:34:51 AM
Old 03-19-2002
I wonder if you speak about two kinds of 'characters' lets say that an array contains

"ABCD" - those are four characters.
If you treat that as an integer you get the number
1145258561, or 0x44434241 - this is probaby what the original poster meant - _converted_ to characters, a number will take more space.
But any sequence of bytes can be seen as anything, char, float, char*, struct foo*,

So, when a network protocol sends 'characters'- you can make those characters mean anything you want, put two together, and you have a 16 bit short, etc.
But beware of how your machine stores integers!
The bytes above may have looked like
"BADC" on some machines to give the same number!
If I am not mistaken, I think the IBM PC is one of them ...

Look at
man htonl
man htons

Then you will understand why it just sends 'characters'- to make it an 'int'you use one of those functions, that puts the bytes in the right 'network'order, and put them back to local 'machine' order.


I often randomize characters with the % operator.

rand() % 10 gives 0-9

rand() % ('z'-'a') + 'a' is also an interesting contruct

Some fun: Remember that characters, int, floats and all that are really just bits.
If you want char is a certain range, maybe you can just chop off some bits!
0123456701234567
1001010011101011
0000111110000000 <- maybe you just want those
-----------------
0000010010000000

This would make it fast by just using one machine op,

AND byte, 000011111

Last edited by AtleRamsli; 03-19-2002 at 07:27 AM..
 

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UUENCODE(5)							File Formats Manual						       UUENCODE(5)

NAME
uuencode - format of an encoded uuencode file DESCRIPTION
Files output by uuencode(1C) consist of a header line, followed by a number of body lines, and a trailer line. Uudecode(1C) will ignore any lines preceding the header or following the trailer. Lines preceding a header must not, of course, look like a header. The header line is distinguished by having the first 6 characters "begin ". The word begin is followed by a mode (in octal), and a string which names the remote file. A space separates the three items in the header line. The body consists of a number of lines, each at most 62 characters long (including the trailing newline). These consist of a character count, followed by encoded characters, followed by a newline. The character count is a single printing character, and represents an inte- ger, the number of bytes the rest of the line represents. Such integers are always in the range from 0 to 63 and can be determined by sub- tracting the character space (octal 40) from the character. Groups of 3 bytes are stored in 4 characters, 6 bits per character. All are offset by a space to make the characters printing. The last line may be shorter than the normal 45 bytes. If the size is not a multiple of 3, this fact can be determined by the value of the count on the last line. Extra garbage will be included to make the character count a multiple of 4. The body is terminated by a line with a count of zero. This line consists of one ASCII space. The trailer line consists of "end" on a line by itself. SEE ALSO
uuencode(1C), uudecode(1C), uusend(1C), uucp(1C), mail(1) 7th Edition May 15, 1985 UUENCODE(5)
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