Re: discovering code points with embedded nulls

From: Jim Allan (
Date: Thu Feb 06 2003 - 15:19:30 EST

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    Doug Ewell posted:

    > The use of NULL to terminate strings is a basic part of the Standard C
    > library, not just certain APIs. As such, it doesn't seem right to call
    > this a "misuse" of the character.

    But ISO 646, in defining ASCII, states as the defintion of the control
    character NULL:

    "A control character used to accomplish media-fill or time-fill. Null
    characters may be inserted into or removed from a stream of data without
    affecting the information content of that stream. But then the addition
    or removal of these characters may affect the information layout and/or
    the control of equipment."

    Its basic use was for block filling and on text terminals for filling
    screen memory before use. The definition also allowed for unpunched
    areas on punched tape to be ignored.

    The use of NULL in C and Unix as a string terminator is certainly a
    misuse of the NULL character as orginally defined.

    It amuses me to think of this, and also the use in C of LF only for what
    in ISO 646 would require the use of CR + LF, when Unix people sometimes
    rant about Microsoft and Macintosh computers not properly following

    Jim Allan

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