||Changes the line number in error messages
#line digits string
The #line directive changes the
compiler's notion of the current filename and line
number. The first form changes the line number (as expressed by the
_ _LINE_ _ directive and used in error messages)
to digits. The second form changes the
line number to digits and the filename to
the contents of string. The new file name
is used as the value of the _ _FILE_ _ macro.
The #line directive is typically used by programs
that generate C++ as output from some other input. The directive
records the original filename and line number that produced the C++
code. Error messages and debuggers can point to the original file
instead of to the intermediate C++ source file.