diff -Naur ddd-3.3.12-orig/ddd/strclass.C ddd-3.3.12/ddd/strclass.C
--- ddd-3.3.12-orig/ddd/strclass.C	2019-02-07 16:29:46.000000000 +0300
+++ ddd-3.3.12/ddd/strclass.C	2019-05-06 08:46:41.686853108 +0300
@@ -35,6 +35,7 @@
 
 #include "strclass.h"
 #include "config.h"
+#include <cstdio>
 #include <ctype.h>
 #include <limits.h>
 #include <new>