Confused about standard identifier naming

Question

reading a book, it says that these two are obligate conventions:

• do not use underscore in identifiers
• identifier should not begin with capital letter

But in many places then I can see, especially in properties, that author does not follow that, e.g.:

private int x

and

public int X..

The same with underscores..sometimes he uses _x and X for properties.

What is the correct naming convention, please?

Answer 1

The rules are not the same for all identifiers. And there are multiple standards around, all are good as long as they are used consistently.

What I remember from the MS guidelines:

• class (type) names and public members use PascalCasing
• private members, local vars and parameters use camelCasing

But camelCasing just means "don't start with a capital", field, _field, mField and m_field all qualify.