declaring static variables in a function

gcc 4.4.2 c89

I am have been re-engineering some one else's source code.

In a function someone has declared some static variables, but doesn't seem to serve any purpose of having them static. I am just wondering if my comment below would be accurate?

static char tempstr[64]; 

For my understanding when declaring static variables inside a function it will retain is scope so acts like a global variable.

Also, if the static variable is declared in global scope, then its scope is limited to the file only.

Many thanks for an开发者_运维技巧y suggestions,

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If I understand your interpretation, it is accurate.

Inside a function static means "allocate data segment memory so the value persists between function calls and so that all function instances (think, recursion or threads) share the same actual storage."

This matters a lot if a previous value is used in a later function call or if a reference is leaked out of the function by an external call or by returning a pointer.

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Yes, your interpretation is correct. Except that be careful with what you call "acts like a global". It acts like a global only in the sense that it retains values between calls, but it's not globally visible, but still only in the function that declared it.

Also see this question.

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It doesn't make it a global. Its still a local variable it just retains its value during successive calls.

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That's correct. One more aspect to keep in mind is that if your code is multi-threaded, all the threads will share the same copy of the variable, so it is technically possible that the original designer used that variable as a cross-thread communication mechanism. I don't advocate that technique, but I can't rule it out without more information.