What are the issues when dealing with special values - 64 bits for instance?

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Examples edit

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
 }

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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).