C++: strcpy Function copies null?

While using string manipulation functions specificaly strcpy I did this small program.

char s1[8]="Hellopo";
char s2[4]="sup";
strcpy(s1,s2);
cout<<s1<<endl;

When I printed out s1 It actually just printed out "sup". I expected it to print "suplopo".

Then I did this:

cout<<s1+4 << endl;

It printed out "opo";

And The output of this: cout<<s1+3<<endl; was nothing

So after thinking a bit about it.

I came to this conclusion. Since C++ stops outputing the string once it reaches the null terminator. Therefore the null must have been copied in the strcpy function. Resulting in this string:

s - u - p - \0 - o - p - o -\0;

Please tell me if this is correct or not. And if im not please correct me.

And if you have any more info to provide please do.