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    SubjectRe: gcc fixed size char array initialization bug - known?
    Guennadi Liakhovetski wrote:
    > On Thu, 2 Aug 2007, Andi Kleen wrote:
    >> of C99:
    >> ``
    >> An array of character type may be initialized by a character string literal, optionally
    >> enclosed in braces. Successive characters of the character string literal (including the
    >> terminating null character if there is room or if the array is of unknown size) initialize the
    >> elements of the array.
    >> ''
    >> Note the "if there is room".
    >> I believe the rationale is that it still allows to conveniently initialize
    >> non zero terminated strings.
    > Right, I accept that it will compile, but I don't understand why "01234"
    > produces a warning and "0123" doesn't? Don't think C99 says anything about

    How should gcc know whether you actually wanted that char foo[len] to
    contain a \0 as last element?

    Given the respective command line switches, gcc does warn in some cases
    where it is guesswork whether what you typed is what you intended. For

    if (i = j())

    is reason for gcc to warn even if that might exactly be what you wanted.
    However this construct can easily be annotated as

    if ((i = j()))

    to show to gcc and to carbon-based bipedals that you indeed wanted this.

    Now there is no nice way to make an annotation that says "look, I'm
    going to initialize an array of char with a string literal now, and the
    resulting array will contain a non-zero member as last element, and I
    mean it". And since there is no such annotation possible, gcc does not
    warn and demand that you annotate the perfectly valid and 100%
    spec-compliant construct char a[4] = "1234";.
    Stefan Richter
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      Last update: 2007-08-03 00:19    [W:2.847 / U:0.816 seconds]
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