binary - Insert and extract fields from binary strings
(Dissect and join binary data into/from tcl values)
http://purl.org/tcl/home/man/tcl8.4/TclCmd/binary.htm
This is the primary command to use when Working with binary data.
For dealing with binary data on C level see also http://www.tcl.tk/man/tcl8.4/TclLib/ByteArrObj.htm
See Binary representation of numbers or bitstrings for examples of usage.
What are the issues when dealing with special values - 64 bits for instance?
See also:
Examples
In a conversation in the Tcl'ers Chat about how to display the bits in a number DKF came up with this:
binary scan [binary format I $value] B32 x; set x
GPS: I use the following string to/from hex conversion procedures to store files that may contain special characters that interfere with the OS filesystem in my Grindweb program:
proc convert.string.to.hex str {
binary scan $str H* hex
return $hex
}
proc convert.hex.to.string hex {
foreach c [split $hex ""] {
if {![string is xdigit $c]} {
return "#invalid $hex"
}
}
binary format H* $hex
}Q. Is there a way to display the ASCII equivalent of characters in a string?
A.
set chrs "abc" binary scan [encoding convertto ascii $chrs] c* x puts $x 97 98 99
results in the translation of the characters to hex being assigned to $x. If the characters are some encoding other than ASCII, just change the ascii to the appropriate encoding name.
DKF: Also consider using [scan $str %c] for single characters where you want the UNICODE character number (which is the same as the ASCII one for ASCII characters, and the same as the ISO8859-1 codepoint too, since UNICODE is a superset of ISO8859-1 and that in turn is a superset of ASCII).