I'm using bison & flex (downloaded via cygwin) with vc++. When I compile the program I got an error:
...: fatal error C1083: Cannot open include file: 'unistd.h': No such file or directory
The corresponding code in the flex-generated file is:
#ifndef YY_NO_UNISTD_H
/* Special case for "unistd.h", since it is non-ANSI. We include it way
* down here because we want the user's section 1 to have been scanned first.
* The user has a chance to override it with an option.
*/
/* %if-c-only */
#include <unistd.h>
/* %endif */
/* %if-c++-only */
/* %endif */
#endif
If I define YY_NO_UNISTD_H in the flex file(.l) this error will disappear, but I get several other errors:
...: error C2447: '{' : missing function header (old-style formal list?)
...: warning C4018: '<' : signed/unsigned mismatch
...: error C3861: 'isatty': identifier not found
How can I fix this problem?
All these errors occur in the flex-generated scanner.
I know it's because unistd.h doesn't exist in windows. Do I have to write my own unistd.h? If so how to write it in order to eliminate those errors?
isatty is used by the lexer to determine if the input stream is a terminal or a pipe/file. The lexer uses this information to change its caching behavior (the lexer reads large chunks of the input when it is not a terminal). If you know that your program will never be used in an interactive kind, you can add %option never-interactive to you lexer. When the program is run with user input, use %option interactive. When both uses are desired, you can either generate an interactive lexer, which gives a performance loss when used in batch mode, or provide your own isatty function.