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Iterating Through Struct and Class Members
C provides various mechanisms to iterate through the members of structs and classes. To achieve this, you can employ several techniques.
Defining the Struct with a Macro:
One approach is to use the REFLECTABLE macro, as seen in the following example:
<code class="cpp">struct A { REFLECTABLE ( (int) a, (int) b, (int) c ) };</code>
By using this macro, you can conveniently iterate over the fields and print their values as follows:
<code class="cpp">struct print_visitor { template<class FieldData> void operator()(FieldData f) { std::cout << f.name() << "=" << f.get() << std::endl; } }; template<class T> void print_fields(T & x) { visit_each(x, print_visitor()); } A x; print_fields(x);</code>
Adapting the Struct as a Fusion Sequence:
Another option is to adapt the struct as a Boost.Fusion sequence. Consider the following example:
<code class="cpp">struct A { int a; int b; int c; }; BOOST_FUSION_ADAPT_STRUCT ( A, (int, a) (int, b) (int, c) )</code>
With this adaptation, you can iterate over the fields using the following code:
<code class="cpp">struct print_visitor { template<class Index, class C> void operator()(Index, C & c) { std::cout << boost::fusion::extension::struct_member_name<C, Index::value>::call() << "=" << boost:::fusion::at<Index>(c) << std::endl; } }; template<class C> void print_fields(C & c) { typedef boost::mpl::range_c<int,0, boost::fusion::result_of::size<C>::type::value> range; boost::mpl::for_each<range>(boost::bind<void>(print_visitor(), boost::ref(c), _1)); }</code>
These techniques allow you to effectively iterate through struct and class members in C .
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