While left shift operator (<<) using before std::cout , what does it work for?

Question

Those code lines:

std::cout << "observerIndex : " <<
std::cout << pobserverIndex -> observerInt() ;

Generate the compiler error below:

file.C:2917:37: error: no match for 'operator<<' (operand types are 'std::basic_ostream<char>' and 'std::basic_ostream<char>')
     std::cout << "observerIndex : " <<
                                     ^

Could anyone please tell me what left shift operator( << ) is doing on there (before std::cout << pobserverIndex -> observerInt() )?

Answer 1

You appear to be missing a semicolon at the end of your first statement, plus you are repeating std::cout .

You need to use

std::cout << "observerIndex: " << pobserverIndex -> observerInt(); 

A variant like

std::cout << "a" << std::cout<< "b";

is outputting the address of the object cout in the std namespace, formatted as hexadecimal, between the strings "a" and "b".