Guys wanted to ask what is name space std that is used before main ()

Answer 1

Simply stated, C++ has lots of packages. So, "cout" are part of the "std" (standard) package. The statement "using namespace std" means that all called functions that aren't already defined will be called from std. Otherwise, you would have to say std::cout instead of cout.

Answer 2

but dude:: symbol is used for scope resolution operator what is the reletion b/w them