What can be replaced with using namespace std;

Answer 1

with "using namespace std;"
#include <iostream>
using namespace std;
int main() {
cout << "Hello" << endl;
}
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without "using namespace std;"
#include <iostream>
int main() {
std::cout << "Hello" << std::endl;
}

Answer 2

if you don't wanna use 'using namespace std;' then you need to std:: in each in every line in the cout and arrays without that std!