c++ - What does object.operator do? -

this question has answer here:

• why explicitly calling operator<< on std::cout cause unexpected output? 2 answers

i saw following code:

cout.operator << ("hello"); 

and thought same as:

cout << "hello"; 

but prints:

0x46e030 

how work? can do?

object.operator<<(??); not quite same std::ostream::operator<<(std::ostream&, ??), because excludes non-member (free) functions.

the std::ostream::operator<< members are:

basic_ostream& operator<<( short value ); basic_ostream& operator<<( unsigned short value ); basic_ostream& operator<<( int value ); basic_ostream& operator<<( unsigned int value ); basic_ostream& operator<<( long value ); basic_ostream& operator<<( unsigned long value ); basic_ostream& operator<<( long long value ); basic_ostream& operator<<( unsigned long long value ); basic_ostream& operator<<( float value ); basic_ostream& operator<<( double value ); basic_ostream& operator<<( long double value ); basic_ostream& operator<<( bool value ); basic_ostream& operator<<( const void* value ); basic_ostream& operator<<( std::basic_streambuf<chart, traits>* sb); basic_ostream& operator<<( basic_ostream& st, std::ios_base& (*func)(std::ios_base&) ); basic_ostream& operator<<( basic_ostream& st, std::basic_ios<chart,traits>& (*func)(std::basic_ios<chart,traits>&) ); basic_ostream& operator<<( basic_ostream& st, std::basic_ostream& (*func)(std::basic_ostream&) ); 

the lack of const char* might seem confusing, recall can add free operator<< functions well, in addition above members. <ostream> includes these:

ostream& operator<<( ostream& os, chart ch ); ostream& operator<<( ostream& os, char ch ); ostream& operator<<( ostream& os, char ch ); ostream& operator<<( ostream& os, signed char ch ); ostream& operator<<( ostream& os, unsigned char ch ); ostream& operator<<( ostream& os, const chart* s ); ostream& operator<<( ostream& os, const char* s ); ostream& operator<<( ostream& os, const char* s ); ostream& operator<<( ostream& os, const signed char* s ); ostream& operator<<( ostream& os, const unsigned char* s ); template< class t > ostream& operator<<( ostream&& os, const t& value ); 

by specifically calling out object.operator<<(??) overload, you've told explicitly not use free functions, , use use member functions. best match "hello" void* overload, printed address of string.