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PO"extern" inside a function?
 

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    <p>Well, reading "a bit old" book ("The C programming language", second edition, by Dennis Ritchie), I came a cross the following:</p> <blockquote> <p>An external variable must be defined, exactly once, outside of any function; this sets aside storage for it. The variable must also be declared in each function that wants to access it</p> </blockquote> <p>and I was like - <em>what?!</em> </p> <p>"The variable must also be declared in each function that wants to access it". Then, I was shocked one more time:</p> <pre><code>int max; /* ... */ int main() { extern int max; /* ... */ } </code></pre> <p>And one more - <em>what?!</em></p> <hr> <p>As far as I know (obviously, it's not much and far from enough), <code>extern</code> makes sense only when you define a global variable somewhere and you want to access it through another file (not to define it again).</p> <p>So:</p> <ul> <li>What's the point of this <code>extern int max</code> <em>inside</em> the <code>main</code> or any other function?</li> <li>Does the standard <em>really</em> says, that this is a <em>must</em> (that I need to declare, for this example, this <em>max</em> in each function, that will use it?)</li> <li>Is this the same for C++ (that's why I placed the C++ tag)? This is the first time I see something like this.</li> </ul> <p>Note: this is not the same as <a href="https://stackoverflow.com/questions/9686198/what-is-the-use-of-declaring-a-static-variable-as-extern-inside-a-function">What is the use of declaring a static variable as extern inside a function?</a> </p>
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    1. USKiril Kirov
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    1. COAmazon.com says K&R 2nd ed. was published in 1988. I'd guess the standard has changed a bit since then. :)
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    2. COYep, I know the year of publishing, that's what I thought, but I wanted to ask, just to be sure. That's why I asked for a confirmation from the ISO standard.
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    3. CO@KirilKirov you need quotes from C or C++ standard?
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