What is namespace in c plus plus program?

A namespace is similar to a class in object oriented programming. A namespace contains functions defined by the programmer. for example namespace std contains functions like cout and cin.

namespaces can be globaly declared like so: "using namespace std;"
which includes all the functions located in the namespace std.
if you only need to use cout you can globaly declare only cout like this "using std::cout;"

or

std::cout<<"calling cout directly from namespace std";

you can make your own namespaces as well

namespace mynamespace;
void myfunction(){
code for function
}

and use it

using mynamespace::myfunction;


The main use of a namespace is to reduce or eliminate collisions with names that may be duplicated but have different functionality. For example, I may want to use an object with the name of 'cout', but that name already exists. If I place it in a different namespace I would be able to use it with that name.