C++ Templates – Understanding Typename and Class Keywords

c++templates

What is the difference between writing a template in c++ in the below both ways

template<typename T> & template<class T>

and when do we prefer them above each other?
If both are same,then why do we have them both if one is enough?

No difference at all. I prefer first one (mostly), but that is my personal taste. The language doesn't make any difference between them.

For template parameters, the keywords typename and class are equivalent. §14.1.2 says:

There is no semantic difference between class and typename in a template-parameter.

If both are same,then why do we have them both if one is enough?

Stan Lippman explains this in his article: