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    <p>Continued from the comments above...</p> <p>(1) The <code>pthread_create</code> start function (3rd parameter) <em>must</em> have a signature of </p> <pre><code>void *(*start_routine) (void *) </code></pre> <p>that is, a function that takes a void pointer and returns a void pointer. For example:</p> <pre><code>void* myfunc(void *) </code></pre> <p>You are getting compile errors because your start function probably (and incorrectly) looks like this:</p> <pre><code>void myfunc(void) </code></pre> <p>in other words a function that takes <em>no</em> parameters and returns no result. You got around this compiler error by casting myfunc to a pointer to void but it is unnecessary and wrong. Your real problem is that your start function "myfunc" has the wrong signature.</p> <p>(2) It seems you are hung up on void and pointers to void. There several good answers here on this including <a href="https://stackoverflow.com/questions/11626786/what-does-void-mean-and-how-to-use-it">this</a>. Basically a pointer to void is a generic pointer that can point to <em>any</em> type. </p> <p><code>pthread_create</code> is itself an excellent example of the use of void ptrs. Because there is no way for a start function to know what kind of data a developer wants to pass into (and return) from the function they use a void ptr that can point to any type. It is up to the developer of the start function to then cast the void ptr to appropriate type he actually passed before using whatever the void ptr points to. So now the start function can process a ptr that may in actually point to an int, a double, an array, a structure, or whatever.</p> <p>In your case you are turning a pointer to a function with a specific signature into a pointer to anything. This may satisfy the compiler because it assumes you know what you are doing. But in this instance you don't because you are papering over the real error which is that the signature of your start function is wrong. </p>
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    1. CO@ Duck. Thanks.got it. I will tell you my understanding. please let me know whether it is correct or not. The function prototype should match this format[void *(*start_routine) (void *)]. If not, we should typecast it accordingly and give as an argument to pthread_create.
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    2. CO@ Duck. I have another doubt also.. In this link https://computing.llnl.gov/tutorials/pthreads/samples/hello.c in the statement rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t); the coder has just passed a variable as 4th argument without passing address of that variable. Is this code correct?? If yes how can we cast a variable to void *.
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    3. COOn the 1st, no, I don't think you understand. The start function *has* to have that signature. That's the *one and only* acceptable sig. You *can not* cast your way out of it. And there is no point. As is, it is a func that takes anything and returns anything. It couldn't be more flexible. I'll get to your other Q in a bit when I have time.
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