 <p>You only have to use this-> if you have a symbol with the same name in two potential namespaces. Take for example:</p> <pre><code>class A { public: void setMyVar(int); void doStuff(); private: int myVar; } void A::setMyVar(int myVar) { this-&gt;myVar = myVar; // &lt;- Interesting point in the code } void A::doStuff() { int myVar = ::calculateSomething(); this-&gt;myVar = myVar; // &lt;- Interesting point in the code } </code></pre> <p>At the interesting points in the code, referring to myVar will refer to the local (parameter or variable) myVar. In order to access the class member also called myVar, you need to explicitly use "this->".</p>