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PODifference between the * and & operator in function calls
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  1. PODifference between the * and & operator in function calls
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    copied!<blockquote> <p><strong>Possible Duplicate:</strong><br> <a href="https://stackoverflow.com/questions/670101/c-functions-ampersand-vs-asterisk">C++ functions: ampersand vs asterisk</a><br> <a href="https://stackoverflow.com/questions/9636903/what-are-the-distinctions-between-the-various-symbols-etc-combined-with-p">What are the distinctions between the various symbols (*,&amp;, etc) combined with parameters?</a> </p> </blockquote> <p>I am wondering the difference between the address operator <code>&amp;</code> and the deference operator <code>*</code> in a C++ function call. For example take the following function</p> <pre><code>void foo (std::string&amp; param) { param = "Bar."; std::cout &lt;&lt; param.size(); } </code></pre> <p>and let's call it in our <code>main()</code> function like so...</p> <pre><code>int main() { std::string test; foo(test); //Why not foo(&amp;test)? std::cout &lt;&lt; test; //Prints out the value "Bar." } </code></pre> <p>First off, why does the <code>&amp;</code> operator allow me to assign a value as if it were a pointer (assigning it a value that survives the RAII and scope of the function <code>foo()</code> when it's not a pointer) as it is able to be printed out in my <code>main()</code> function even though it's not <code>static</code>? I am assuming it is not a pointer because I am able to access the <code>size()</code> method by using the <code>.</code> operator instead of the <code>-&gt;</code> which is used for pointers.</p> <p>Secondly, what would be the difference between using the <code>&amp;</code> operator in a function parameter vs. using the <code>*</code> operator? Is it even different than just a plain variable like <code>std::string param</code>? It appears to be called like that (<code>foo(test)</code> instead of <code>foo(&amp;test)</code>).</p>
 

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