#line

Syntax:

    #line line_number "filename"

The #line command is simply used to change the value of the __LINE__ and __FILE__ variables. The filename is optional. The __LINE__ and __FILE__ variables represent the current file and which line is being read. The command

     #line 10 "main.cpp"

…changes the current line number to 10, and the current file to “main.cpp”.