Talk:Graphic character

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Status of space[edit]

"The space is considered to be both a graphic character and a control character[citation needed] in ISO 646; this is probably due to it having a visible form on computer terminals but a control function (of moving the print head) on teletypes. [original research?]"

I can see what this is saying. In some respects the space would be considered a graphic character:

  • it has a visual representation
  • as such, where code 32 appears in the buffer of a text-mode VDU whose character set is ASCII or any superset thereof, one can be sure what to expect to see in that character cell
  • fonts are likely to contain a glyph for it, even if that glyph has the appearance of a blank space (though this may depend on the platform); in any case, the character would have a width
  • programming languages, database systems, etc. invariably allow it to be included within a string (if they support strings at all)

In other respects it is special:

  • it is sometimes represented by a "control code" such as SP, in line with the control codes for ASCII characters 0-31 and 127.
  • in the syntax of many text-based data formats and programming languages, it is a whitespace character just like CR, LF and HT
  • in most modern programs that support multi-line display and/or editing of text (word processors, web browsers, text editors, email clients, etc.), it is treated specially in order to achieve word-wrapping and (in some cases) justification
  • a daisywheel probably wouldn't include a petal for space; rather, the printer would be likely to just advance the print head when it receives a space character (this is perhaps the basis of the statement about teletypes).

Ironically, there are standard C functions iscntrl and isgraph, which consider the space to be neither a control character nor a graphic character, which is the opposite of this statement.

I suppose the only real conclusion of this is that the status of the space depends on your point of view. Still, we ought to find a link for the ISO standard on this. Moreover, the use of "probably" implies that the reason given is speculation, rather than research, so I'm not sure that tagging it with {{or}} is right.

What do people think we should do with the statement? — Smjg (talk) 02:06, 4 May 2013 (UTC)