Re: using local static variable inside a function

James Kanze <>
Fri, 2 Oct 2009 01:27:45 -0700 (PDT)
On Oct 2, 8:24 am, "Christian Freund" <> wrote:

Once again: the standard tells where to store the static
content and how often.

Only to a point. The standard gives the implementation the
right to do anything it pleases if the code contains undefined
behavior. Calling pthread_create or CreateThread results in
undefined behavior, according to the standard, so nothing the
compiler does in a multithreaded program will break conformance.

But that's really being overly pedantic. Compilers do support
threading. It just means that for the definition of what
happens in a multithreaded program, you have to look to the
compiler documentation, and not the standard. And you can
exterpolate to more or less define what you should be able to
reasonably expect---what would be a logical choice of options
for the compiler, or what you would expect from a QoI point of

So by that it implicitly defines static content in functions
not very thread safe.

It doesn't imply anything. Obviously, if the function is called
from multiple threads, you have to treat the static variable as
you would any variable that is accessed from different threads,
but that's about it; there's no reason for there to be any
difference between local statics and other variables with static

James Kanze

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