why we use using namespace std in a program

Question

explain

Answer 1

useing namespace std tells the compiler to use the standard namespace library's, it is not nessary to put it at the top of your code, and most more advanced programs written in c++ do not. however you do need to tell the compiler what namespace you are useing, this can be done inline, for example

#include <iostream>
int main ()
{
std::cout "hello ";
std::cout "world";
return 0;
}

Answer 2

“std” just like ”your” dog and “my” dog, let our kown “who's” dog.