Do we have to use using namespace std if we have written end1 in the code?

Answer 1

yes
if you want to use it without using namespace std ,

std::cout<<"Hello"<<std::endl;

or just use \n instead

std::cout<<"Hello\n";

Answer 2

Osama Samir
[not to distract, this is just trivia]

endl is a stream manipulator* and also flushes the output buffer.
\n is just a replaced special character and does not flush.

* http://www.cplusplus.com/reference/iostream/manipulators
* http://www.cplusplus.com/reference/ostream/endl/

Answer 3

Thanks Kirk Schafer that is a new information to me

Answer 4

I assume that you're taking about endl (end line ) not end1( end one ) !
yes , you can do without
It just make new line
Edit:
look at Kirk Schafer comment

Answer 5

Is there any need to write end1? without that also we can execute the program..