--- /dev/null
+void print(...) = #1;
+string ftos (float) = #2;
+
+void test(string s) {
+ print(ftos(!s));
+ if (s) print(" on");
+ if (!s) print(" off");
+ if (!!s) print(" !!on");
+ print("\n");
+}
+
+void test2(string s) {
+ print(ftos(!s));
+ while (s) { print(" on"); break; }
+ while (!s) { print(" off"); break; }
+ while (!!s) { print(" !!on"); break; }
+ print("\n");
+}
+
+string str_nul;
+
+void main(vector v) {
+ test("foo");
+ test2("foo");
+ test("");
+ test2("");
+ test(str_nul);
+ test2(str_nul);
+}