| ;; Call with standard output |
| (print-int (current-output-port) 314159) |
| |
| ;; Redirection to a file. Note that the port is automatically flushed |
| ;; (via force-output) before calling the C function, and that the C |
| ;; function gets a temporary "FILE" stream, which is closed after the |
| ;; call. So you can simply mix Scheme and C output. |
| (with-output-to-file "test.out" |
| (lambda () |
| (display 4711) |
| (newline) |
| (print-int (current-output-port) 314159) |
| (display 815) |
| (newline))) |
| |
| ;; Redirection to a string or soft port won't work -- |
| ;; we can only handle file ports. |
| (catch #t |
| (lambda () |
| (with-output-to-string |
| (lambda () |
| (print-int (current-output-port) 314159)))) |
| (lambda args |
| (display "Below shows that attempting to write to a string or soft port will result in a wrong-type-error...") |
| (newline) |
| (write args) (newline))) |
| |
| ;; Read from a file port. Note that it is a bad idea to mix Scheme and |
| ;; C input because of buffering, hence the call to seek to rewind the file. |
| (with-input-from-file "test.out" |
| (lambda () |
| (seek (current-input-port) 0 SEEK_SET) |
| (display (read-int (current-input-port))) |
| (newline))) |
| |
