Why use prefixes on member variables in C++ classes

Question

A lot of C++ code uses syntactical conventions for marking up member variables. Common examples include

• m_memberName for public members (where public

Answer 1

You have to be careful with using a leading underscore. A leading underscore before a capital letter in a word is reserved. For example:

_Foo

_L

are all reserved words while

_foo

_l

are not. There are other situations where leading underscores before lowercase letters are not allowed. In my specific case, I found the _L happened to be reserved by Visual C++ 2005 and the clash created some unexpected results.

I am on the fence about how useful it is to mark up local variables.

Here is a link about which identifiers are reserved: What are the rules about using an underscore in a C++ identifier?