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PODeclaring and defining a function object inside a class member function
 

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  1. PODeclaring and defining a function object inside a class member function
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    <p>I wonder if and how it is possible to define a function object inside a classes member function to use it directly with, for example, the std::transform function.<br> I know the example is a bit stupid, it's just to show the problem I'm confronted with. </p> <p>File "example.h"</p> <pre><code>class Example { public: //.. constructor and destructor stuff std::string toString() const; //Converts 'mVal' to a std::string private: std::vector&lt;int&gt; mVal; //Only one digit numbers are allowed ([0-9]) } </code></pre> <p>File "example.cpp"</p> <pre><code>std::string Example::toString() const { //The functor which should be used in std::transform struct { char operator()(const int number) { char c; //"Convert" 'number' to a char return c; }; } functor; //Transform the integers to char std::string str(mVal.size(), '0'); //Allocate enough space std::transform(mVal.begin(), mVal.end(), str.begin(), functor); return str; };//toString() </code></pre> <p>Ever since I tried to implement a function object directly inside a member function like in "example.cpp", the code doesn't get compiled. The error message I get is:</p> <pre><code>error: no matching function for call to ‘transform(__gnu_cxx::__normal_iterator&lt;const int*, std::vector&lt;int, std::allocator&lt;int&gt; &gt; &gt;, __gnu_cxx::__normal_iterator&lt;const int*, std::vector&lt;int, std::allocator&lt;int&gt; &gt; &gt;, __gnu_cxx::__normal_iterator&lt;char*, std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; &gt;, Example::toString() const::&lt;anonymous struct&gt;&amp;)’ </code></pre> <p>So I think the problem comes up when using the struct "functor" in std::transform. Can someone tell me what the problem is?</p> <p>Using:<br> gcc-4.2 compiler under Ubuntu Linux.</p> <p>Thanks in advance,<br> René.</p>
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    1. COSee http://stackoverflow.com/questions/2662843/c-can-local-class-reference-be-passed-to-a-function
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    2. COpossible duplicate of [Using local classes with STL algorithms](http://stackoverflow.com/questions/742607/using-local-classes-with-stl-algorithms)
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      1. USDavid Rodríguez - dribeas
    3. COYes, you're right. Didn't know the exact search terms.
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