# Boost Exception

### diagnostic_information

#include <boost/exception/diagnostic_information.hpp>

    namespace
    boost
        {
        std::string diagnostic_information( boost::exception const & x );
        }

#### Returns:

This function iterates over all data objects stored in the boost::exception through operator<<. The returned string is constructed by converting each data object to string and then concatenating these strings together.

When the error_info<Tag,T> template is instantiated, the system attempts overload resolution for an unqualified call to to_string(x), where x is of type T. If this is successful, the to_string overload is expected to return std::string and is used to convert objects of type T to string.

Otherwise, the system attempts overload resolution for s << x, where s is a std::ostringstream and x is of type T. If this is successful, the operator<< overload is used to convert objects of type T to string.

Otherwise the system is unable to convert objects of type T to string, and an unspecified stub string value is used without issuing a compile error.

#### Notes:

- The format of the returned string is unspecified.
- The returned string is not user-friendly.
- If dynamic_cast<std::exception const *>(&x) is not null, the returned string includes the output from std::exception::what.
- The returned string may include additional platform-specific diagnostic information.

### See Also:

BOOST_THROW_EXCEPTION
Boost Exception
boost/exception/diagnostic_information.hpp
Diagnostic Information