compiling .cpp with gcc

okay this I did accidentally , compiling .cpp using gcc and not g++

but I actually want to understand the console output, line by line, if it has any sense.

struct a{
   int pointer;
   int  rollno;
};

struct a student,*studentref;
studentref = &student;
studentref->rollno = 141; 
studentref->pointer = 8;

cout<<studentref->rollno<<") : "<<studentref->pointer<<endl;

compiling this code with gcc structpointers.cpp -o structp gives the following output:

sourab@sourab:/home/gbear/coding/learningds$ gcc structpointers.cpp -o structp
/tmp/ccXrq1Cv.o: In function `main':
structpointers.cpp:(.text+0x2e): undefined reference to `std::cout'
structpointers.cpp:(.text+0x33): undefined reference to `std::ostream::operator<<(int)'
structpointers.cpp:(.text+0x38): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
structpointers.cpp:(.text+0x40): undefined reference to `std::ostream::operator<<(std::ostream& (*)(std::ostream&))'
/tmp/ccXrq1Cv.o: In function `__static_initialization_and_destruction_0(int, int)':
structpointers.cpp:(.text+0x6e): undefined reference to `std::ios_base::Init::Init()'
structpointers.cpp:(.text+0x7d): undefined reference to `std::ios_base::Init::~Init()'
collect2: error: ld returned 1 exit status