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-rw-r--r--manual/examples/rprintf.c52
1 files changed, 52 insertions, 0 deletions
diff --git a/manual/examples/rprintf.c b/manual/examples/rprintf.c
new file mode 100644
index 0000000000..eff1d8e7cf
--- /dev/null
+++ b/manual/examples/rprintf.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <printf.h>
+#include <stdarg.h>
+
+/*@group*/
+typedef struct
+ {
+ char *name;
+ } Widget;
+/*@end group*/
+
+int
+print_widget (FILE *stream, const struct printf_info *info, va_list *app)
+{
+ Widget *w;
+ char *buffer;
+ int len;
+
+ /* Format the output into a string. */
+ w = va_arg (*app, Widget *);
+ 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
+main (void)
+{
+ /* Make a widget to print. */
+ Widget mywidget;
+ mywidget.name = "mywidget";
+
+ /* Register the print function for widgets. */
+ register_printf_function ('W', print_widget, NULL); /* No arginfo. */
+
+ /* Now print the widget. */
+ printf ("|%W|\n", &mywidget);
+ printf ("|%35W|\n", &mywidget);
+ printf ("|%-35W|\n", &mywidget);
+
+ return 0;
+}