Std::list::sort() doesn't work with custom class

Question

The following example doesn't order a list the way I'd expect. Is this being done wrong? Sun Studio 12 (not update 1). Current patches as of Monday.
#include <list>
class CMyClass
public:
CMyClass(long a) : m_Sec(a) { }
bool operator<(const CMyClass* rhs)
return (m_Sec < rhs->m_Sec);
long m_Sec;
typedef std::list<CMyClass*> TLogList;
int
main(int argc, char* argv[])
TLogList logList;
CMyClass* name = new CMyClass(0x4A833E79);
logList.push_back(name);
name = new CMyClass(0x4A85E144);
logList.push_back(name);
name = new CMyClass(0x4A85E66F);
logList.push_back(name);
name = new CMyClass(0x4A85E66F);
logList.push_back(name);
name = new CMyClass(0x4A85B2C2);
logList.push_back(name);
name = new CMyClass(0x4A85D6EF);
logList.push_back(name);
name = new CMyClass(0x4A69F9AD);
logList.push_back(name);
name = new CMyClass(0x4A85DC92);
logList.push_back(name);
name = new CMyClass(0x4A817316);
logList.push_back(name);
name = new CMyClass(0x4A85DEEB);
logList.push_back(name);
name = new CMyClass(0x4A846329);
logList.push_back(name);
name = new CMyClass(0x4A85E39D);
logList.push_back(name);
name = new CMyClass(0x4A85D41D);
logList.push_back(name);
name = new CMyClass(0x4A89CC17);
logList.push_back(name);
name = new CMyClass(0x4A85DC19);
logList.push_back(name);
logList.sort();
TLogList::iterator logListIter = logList.begin();
TLogList::iterator logListEnd = logList.end();
for (; logListIter != logListEnd; ++logListIter)
CMyClass* name = *logListIter;
cout << hex << name->m_Sec << endl;
return 0;
which produces
4a833e79
4a85e144
4a85e66f
4a85e66f
4a85b2c2
4a85d6ef
4a69f9ad
4a85dc92
4a817316
4a85deeb
4a846329
4a85e39d
4a85d41d
4a89cc17
4a85dc19

Answer 1

The program as you wrote it will sort the contents of the list. The list consists of the addresses of CMyClass objects, and after sorting, will contain those addresses in sorted order.
If you want to sort by the contents of the classes that are pointed to, you need to provide a comparison operator that compares the contents, and use the other form of the list::sort function that takes a comparison function as an argument. That is, add the function
bool comp(const CMyClass* l, const CMyClass* r)
   return l->m_Sec < r->m_Sec;
}and change
logList.sort(); to
logList.sort(comp); This version of list::sort will not compile using the default libCstd, because it requires member templates in the library implementation. For more information about this limitation, refer to the C++ FAQ section on library compatibility.
[http://developers.sun.com/sunstudio/documentation/ss12u1/mr/READMEs/c++_faq.html#LibComp]
The revised code will compile with the optional STLport library, or with other 3rd-party libraries like Apache stdcxx. To use STLport, add the option -library=stlport4 to every CC command, compiling and linking. You cannot mix code compiled for the default libCstd with STLport code in the same program.