The output from the C preprocessor looks much like the input, except that all preprocessor command lines have been replaced with blank lines and all comments with spaces. White-space characters within a line aren't altered; however, a space is inserted after the expansions of most macros. Also, pragmas are passed through verbatim.
Source file name and line number information is conveyed by lines of the form
#
linenum file {digit}
which are inserted as needed into the middle of the input (but never within a string or character constant). Such a line means that the following line originated in file file at line linenum .
After the file name comes zero or more numeric flags: 1, 2 or 3, separated by spaces if multiple flags:
Flag |
Description |
---|---|