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    <p>I suggest that you read up on the documentation for the functions you use. From your comment in James Hopkin's answer, it seems like you don't know what boost::bind does, but simply copy-pasted the code.</p> <p>boost::bind takes a function (call it f), and optionally a number of parameters, and returns a function which, when called, calls f with the specified parameters.</p> <p>That is, <code>boost::bind(threadedAPI1, 0)()</code> (creating a function which takes no arguments and calls threadedAPI1() with the argument 0, and then calling that) is equivalent to <code>threadedAPI1(0)</code>.</p> <p>Since your threadedAPI functions don't actually take any parameters, you can't pass any arguments to them. That is just fundamental C++. You can't call <code>threadedAPI1(0)</code>, but only <code>threadedAPI1()</code>, and yet when you call the function, you try (via boost::bind) to pass the integer 0 as an argument.</p> <p>So the simple answer to your question is to simply define threadedAPI1 as follows:</p> <pre><code>int threadedAPI1(int i); </code></pre> <p>However, one way to avoid the boost::bind calls is to call a functor instead of a free function when launching the thread. Declare a class something like this:</p> <pre><code>struct threadedAPI { threadedAPI(int i) : i(i) {} // A constructor taking the arguments you wish to pass to the thread, and saves them in the class instance. void operator()() { // The () operator is the function that is actually called when the thread starts, and because it is just a regular class member function, it can see the 'i' variable initialized by the constructor cout &lt;&lt; "Thread" &lt;&lt; i &lt;&lt; endl; // No need to create 4 identical functions. We can just reuse this one, and pass a different `i` each time we call it. } private: int i; }; </code></pre> <p>Finally, depending on what you need, plain threads may be better suited than a threadpool. In general, a thread pool only runs a limited number of threads, so it may queue up some tasks until one of its threads finish executing. It is mainly intended for cases where you have many short-lived tasks.</p> <p>If you have a fixed number of longer-duration tasks, creating a dedicated thread for each may be the way to go.</p>
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    1. COthanks, this seems to make a lot of sense. sorry for not reading up on the docs before posting.
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