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POWhat's the meaning of this piece of code? void (*signal(int sig, void (*func)(int)))(int);
 

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  1. POWhat's the meaning of this piece of code? void (*signal(int sig, void (*func)(int)))(int);
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    <p>I came across this piece of code and completely got lost interpreting its meaning.</p> <pre><code>#include &lt;signal.h&gt; void (*signal(int sig, void (*func)(int)))(int); </code></pre> <p>What is a detailed explanation for the code at line 2?</p> <p>I know that <code>void</code> and <code>int</code> are types, the *func is a pointer for a function, and the brackets are for priority. But I still don't get the (*signal ...), the (int), and the whole thing combined together. The more detailed, the better.</p> <p>Probably I've known the meaning/effect of this declaration. But I had to make some more trials to help me understand what's going on, as below:</p> <pre><code> 1 #include &lt;signal.h&gt; 2 void (*signal)(int sig, void (*func)(int)); 3 void (*signal)(int); // then void (signal)(int) again. 4 //void (*signal(int sig, void (*func)(int)))(int); //break this line into two lines above 5 6 int main(){} </code></pre> <p>In the above code, I broke <code>void (*signal(int sig, void (*func)(int)))(int)</code> into two lines. For line 3, I tried both <code>void (*signal)(int)</code> and <code>void (signal)(int)</code>, with the same error result that indicated that I was trying to redeclare <code>signal</code>:</p> <blockquote> <p>TestDeclaration.c:2: error: 'signal' redeclared as different kind of symbol /usr/include/signal.h:93: error: previous declaration of 'signal' was here<br> TestDeclaration.c:3: error: 'signal' redeclared as different kind of symbol /usr/include/signal.h:93: error: previous declaration of 'signal' was here</p> </blockquote> <p>Now I know both the trials are incorrect ways of declaration, but why are they incorrect? Why is the original way of declaration NOT a redeclaration?</p>
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    1. USPeter Mortensen
    1. USphoton
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      1. POWhat's the meaning of this piece of code? void (*signal(int sig, void (*func)(int)))(int);
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      1. POWhat's the meaning of this piece of code? void (*signal(int sig, void (*func)(int)))(int);
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    1. CO+1 for showing that you actually understand *some* of it as opposed to *none* of it.
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      1. POWhat's the meaning of this piece of code? void (*signal(int sig, void (*func)(int)))(int);
      1. USBoltClock
    2. COTry http://www.cdecl.org
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      1. USBjörn Pollex
    3. COFunnily, cdecl.org gives a syntax error on this one. Can someone explain this?
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      1. POWhat's the meaning of this piece of code? void (*signal(int sig, void (*func)(int)))(int);
      1. USBjörn Pollex
 

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