'''string bytelength''' ''string''



** See Also **

   [string]:   

   [string length]:   



** Description **

Returns a decimal string giving the number of bytes used to represent
''string'' in memory.  Because UTF-8 uses one to three bytes to represent
Unicode characters, the byte length will not be the same as the character
length in general. The cases where a script cares about the byte length are
rare.  Refer to the '''Tcl_NumUtfChars''' manual entry for more details on the
UTF-8 representation.

'''In almost all cases, you should use the '''[string length]''' operation
(including determining the length of a Tcl ByteArray object).'''  One example
of when [[`string bytelength`] would be needed appears on the [tcom] page,
where a binary blob is being generated, and [[`string bytelength`] is used to
get the length of the blob without forcing an internal string representation to
be generated, as [[`[string length]`] would do.

Note that (perhaps confusingly) [['''string bytelength''']] should '''not''' be
used with binary data.  This command measures how long the UTF-8 representation
of a string is in bytes.  For binary data you don't want conversion to UTF-8,
so you don't want [['''string bytelength''']] either.  Use [['''[string
length]''']] instead.

[US]: Proof for the sceptical:

======
for {set n 0} {$n < 256} {incr n} {
  lappend cl $n
}
set str [binary format c* $cl]
puts "len : [string length $str]"
puts "blen: [string bytelength $str]"
======

[DKF]: It's not even real UTF-8. It's the length of Tcl's internal encoding
which is ''almost''-UTF8 (i.e., it is consistently denormalized in certain
ways). The only possible use of '''string bytelength''' is answering the
question “How much memory is allocated to hold this value's `bytes` field?”



** Example **

======
string bytelength abc ;# -> 3
======



<<categories>> Tcl syntax | Command | String Processing