Static members of template classes and static members of normal classes

A template class can also define a static member.

As with ordinary classes, defined static members must be defined once in the scope of the definition class.

Otherwise, in the link phase, the compiler cannot recognize the static data members of the class, resulting in unrecognized identifier errors.

It is important to note that each instance of the template class has its own static copy.

This is usually the case when defining static members outside of a class: Template<typename _typ> int class<_typ>::i=0;

All instances of the template class class, static member I, are initialized to zero this time.

When using static members of a template class, this is usually the case: Class::i or class obj; OBJ.I = 3;

That is, an object can invoke a public static member, or you can use a scope operator.