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copied!<p>Given the attention this question / answer receives, and the valuable feedback from <a href="https://stackoverflow.com/questions/281818/unmangling-the-result-of-stdtype-infoname/4541470#comment26629807_4541470">GManNickG</a>, I have cleaned up the code a little bit. Two versions are given: one with C++11 features and another one with only C++98 features.</p> <p>In file <strong>type.hpp</strong></p> <pre class="lang-cpp prettyprint-override"><code>#ifndef TYPE_HPP #define TYPE_HPP #include <string> #include <typeinfo> std::string demangle(const char* name); template <class T> std::string type(const T& t) { return demangle(typeid(t).name()); } #endif </code></pre> <p>In file <strong>type.cpp</strong> (requires C++11)</p> <pre class="lang-cpp prettyprint-override"><code>#include "type.hpp" #ifdef __GNUG__ #include <cstdlib> #include <memory> #include <cxxabi.h> std::string demangle(const char* name) { int status = -4; // some arbitrary value to eliminate the compiler warning // enable c++11 by passing the flag -std=c++11 to g++ std::unique_ptr<char, void(*)(void*)> res { abi::__cxa_demangle(name, NULL, NULL, &status), std::free }; return (status==0) ? res.get() : name ; } #else // does nothing if not g++ std::string demangle(const char* name) { return name; } #endif </code></pre> <p>Usage:</p> <pre class="lang-cpp prettyprint-override"><code>#include <iostream> #include "type.hpp" struct Base { virtual ~Base() {} }; struct Derived : public Base { }; int main() { Base* ptr_base = new Derived(); // Please use smart pointers in YOUR code! std::cout << "Type of ptr_base: " << type(ptr_base) << std::endl; std::cout << "Type of pointee: " << type(*ptr_base) << std::endl; delete ptr_base; } </code></pre> <p>It prints:</p> <p>Type of ptr_base: <code>Base*</code><br> Type of pointee: <code>Derived</code></p> <p>Tested with g++ 4.7.2, g++ 4.9.0 20140302 (experimental), clang++ 3.4 (trunk 184647), clang 3.5 (trunk 202594) on Linux 64 bit and g++ 4.7.2 (Mingw32, Win32 XP SP2).</p> <p>If you cannot use C++11 features, here is how it can be done in C++98, the file <strong>type.cpp</strong> is now:</p> <pre class="lang-cpp prettyprint-override"><code>#include "type.hpp" #ifdef __GNUG__ #include <cstdlib> #include <memory> #include <cxxabi.h> struct handle { char* p; handle(char* ptr) : p(ptr) { } ~handle() { std::free(p); } }; std::string demangle(const char* name) { int status = -4; // some arbitrary value to eliminate the compiler warning handle result( abi::__cxa_demangle(name, NULL, NULL, &status) ); return (status==0) ? result.p : name ; } #else // does nothing if not g++ std::string demangle(const char* name) { return name; } #endif </code></pre> <hr> <hr> <p><em>(Update from Sep 8, 2013)</em></p> <p><a href="https://stackoverflow.com/a/281876/341970">The accepted answer (as of Sep 7, 2013)</a>, when the call to <code>abi::__cxa_demangle()</code> is successful, <strong>returns a pointer to a local, stack allocated array</strong>... ouch!<br> Also note that if you provide a buffer, <code>abi::__cxa_demangle()</code> assumes it to be allocated on the heap. Allocating the buffer on the stack is a bug (from the gnu doc): <em>"If <code>output_buffer</code> is not long enough, it is expanded using <code>realloc</code>."</em> <strong>Calling <code>realloc()</code> on a pointer to the stack</strong>... ouch! (See also <a href="https://stackoverflow.com/questions/281818/unmangling-the-result-of-stdtype-infoname#comment16312718_4541470">Igor Skochinsky</a>'s kind comment.) </p> <p>You can easily verify both of these bugs: just reduce the buffer size in the accepted answer (as of Sep 7, 2013) from 1024 to something smaller, for example 16, and give it something with a name <em>not</em> longer than 15 (so <code>realloc()</code> is <em>not</em> called). Still, depending on your system and the compiler optimizations, the output will be: garbage / nothing / program crash.<br> To verify the second bug: set the buffer size to 1 and call it with something whose name is longer than 1 character. When you run it, the program almost assuredly crashes as it attempts to call <code>realloc()</code> with a pointer to the stack.</p> <hr> <p><em>(The old answer from Dec 27, 2010)</em></p> <p>Important changes made to <a href="https://stackoverflow.com/a/281876/341970">KeithB's code</a>: <strong>the buffer has to be either allocated by malloc or specified as NULL.</strong> Do NOT allocate it on the stack.</p> <p>It's wise to check that status as well.</p> <p>I failed to find <code>HAVE_CXA_DEMANGLE</code>. I check <code>__GNUG__</code> although that does not guarantee that the code will even compile. Anyone has a better idea?</p> <pre class="lang-cpp prettyprint-override"><code>#include <cxxabi.h> const string demangle(const char* name) { int status = -4; char* res = abi::__cxa_demangle(name, NULL, NULL, &status); const char* const demangled_name = (status==0)?res:name; string ret_val(demangled_name); free(res); return ret_val; } </code></pre>

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