1 files changed, 67 insertions, 0 deletions
diff --git a/libc/manual/examples/rprintf.c b/libc/manual/examples/rprintf.c
new file mode 100644
index 000000000..2b8f6bfe7
--- /dev/null
+++ b/libc/manual/examples/rprintf.c
@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <printf.h>
+
+/*@group*/
+typedef struct
+{
+  char *name;
+}
+Widget;
+/*@end group*/
+
+int
+print_widget (FILE *stream,
+	      const struct printf_info *info,
+	      const void *const *args)
+{
+  const Widget *w;
+  char *buffer;
+  int len;
+
+  /* Format the output into a string. */
+  w = *((const Widget **) (args[0]));
+  len = asprintf (&buffer, "<Widget %p: %s>", w, w->name);
+  if (len == -1)
+    return -1;
+
+  /* Pad to the minimum field width and print to the stream. */
+  len = fprintf (stream, "%*s",
+		 (info->left ? -info->width : info->width),
+		 buffer);
+
+  /* Clean up and return. */
+  free (buffer);
+  return len;
+}
+
+
+int
+print_widget_arginfo (const struct printf_info *info, size_t n,
+                      int *argtypes)
+{
+  /* We always take exactly one argument and this is a pointer to the
+     structure..  */
+  if (n > 0)
+    argtypes[0] = PA_POINTER;
+  return 1;
+}
+
+
+int
+main (void)
+{
+  /* Make a widget to print. */
+  Widget mywidget;
+  mywidget.name = "mywidget";
+
+  /* Register the print function for widgets. */
+  register_printf_function ('W', print_widget, print_widget_arginfo);
+
+  /* Now print the widget. */
+  printf ("|%W|\n", &mywidget);
+  printf ("|%35W|\n", &mywidget);
+  printf ("|%-35W|\n", &mywidget);
+
+  return 0;
+}