std::string == operator not working in code : <p>So I am making a simple calculator using c++ which inputs a string from the user and takes that input as the operation.</p>

<pre><code>std::cout&lt;&lt;"Enter your operation: ";
std::string operation;
std::cin&gt;&gt;operation;
while(operation != string("+")|| operation != string("-") || operation != string("*"))
{
    std::cout&lt;&lt;"Invalid operation! Please enter a valid one: ";
    std::cin&gt;&gt;operation;
}
</code></pre>

<p>However no matter what I input, I get the error message "Invalid operation! Please enter a valid one: ".
Please help me out here, thanks!</p>
