Strange comment in C++

As everybody knows you can comment your c++ code with //, but not everybody knows that you can comment the line below using //\

For example:
//\
this line is a comment

[code]//\
//\  //\[/code]

Of course, [code]\[/code] can be used to escape a newline anywhere in C or C++ code, even in comments, strings, and preprocessor directives.