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POHow to implement operator=() for a class that has a reference member variable?
 

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  1. POHow to implement operator=() for a class that has a reference member variable?
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    <p>I want to have an object that contains a reference, and put that object into a vector...</p> <p>Must I use smart pointers instead of a member references in any object I want to push into a vector? This was what I wanted to do:</p> <pre><code>#include &lt;string&gt; #include &lt;vector&gt; using namespace std; class MyClass { public: MyClass(const string&amp; str_ref); //constructor MyClass(const MyClass&amp; mc); //copy constructor private: string&amp; my_str; }; MyClass::MyClass(const string&amp; str_ref) : my_str(str_ref) {} MyClass::MyClass(const MyClass&amp; mc) : my_str(mc.my_str) {} int main() { //create obj and pass in reference string s = "hello"; MyClass my_cls(s); //put into vector vector&lt;MyClass&gt; vec; vec.push_back(my_cls); return 0; } //Throws Error //ref.cpp:6:7: error: non-static reference member ‘std::string&amp; MyClass::my_str’, can’t use default assignment operator </code></pre> <p>However it says I need to implement my own operator=() as the default generated one isn't valid but of course, there is no legal way to do so...</p> <pre><code>#include &lt;string&gt; #include &lt;vector&gt; using namespace std; class MyClass { public: MyClass(const string&amp; str_ref); //constructor MyClass(const MyClass&amp; mc); //copy constructor MyClass operator=(const MyClass&amp; mc); //operator = private: string&amp; my_str; }; MyClass::MyClass(const string&amp; str_ref) : my_str(str_ref) {} MyClass::MyClass(const MyClass&amp; mc) : my_str(mc.my_str) {} //not a constructor. should not construct new object //and return that? MyClass MyClass::operator=(const MyClass&amp; mc) { if (this != &amp;mc) { //test for self-assignment. my_str(mc.my_str); //can't reseat refs. this shouldn't work. } return *this; } int main() { //create obj and pass in reference string s = "hello"; MyClass my_cls(s); //put into vector vector&lt;MyClass&gt; vec; vec.push_back(my_cls); return 0; } //THROWS: //ref2.cpp: In constructor ‘MyClass::MyClass(const string&amp;)’: //ref2.cpp:18:19: error: invalid initialization of reference of type ‘std::string&amp; {aka //std::basic_string&lt;char&gt;&amp;}’ from expression of type ‘const string {aka const //std::basic_string&lt;char&gt;}’ //ref2.cpp: In member function ‘MyClass MyClass::operator=(const MyClass&amp;)’: //ref2.cpp:29:18: error: no match for call to ‘(std::string {aka std::basic_string&lt;char&gt;}) //(std::string&amp;)’ </code></pre> <p>So am I forced to use a smart pointer here or anything other than a reference?</p> <p><strong>EDIT: This is a simplification. String&amp; is not the object being passed, it's a more complex object itself containing a vector object.</strong></p>
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    1. COIs there a particular reason why you wanted to use a string& instead of a plain string?
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    2. COpossible duplicate of [Non-static const member, can't use default assignment operator](http://stackoverflow.com/questions/634662/non-static-const-member-cant-use-default-assignment-operator)
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