how to use string variable for "cs add" command

Hi,

How can I make the following command pass VIM check in _vimrc file?

 

let CodeRoot = “E:/code”

let CscopeDb = CodeRoot . “/cscope.out"

cs add CscopeDb CodeRoot

 

 

the problem is in line 3, cs add only accept direct string but not the variable. For example if I use the following cs add command VIM is fine.

Cs add E:/code/cscope.out E:/code

 

Thanks,

Ray