--- /dev/null
+float test_s_not (string s) { return !s; }
+float test_s_and (string s, string t) { return s && t; }
+float test_s_or (string s, string t) { return s || t; }
+float test_s_if (string s) { if (s) return 1; return 0; }
+float test_s_ifnot(string s) { if not (s) return 1; return 0; }
+
+void test(string s, string t) {
+ print(ftos(!!test_s_not (s)), " ");
+ print(ftos(!!test_s_and (s, t)), " ");
+ print(ftos(!!test_s_or (s, t)), " ");
+ print(ftos(!!test_s_if (s)), " ");
+ print(ftos(!!test_s_ifnot(s)), "\n");
+}
+
+string nuls;
+void main() {
+ print(" ! & | i N\n");
+ print("'str', 'str' -> "); test("FULL", "FULL");
+ print("'str', '' -> "); test("FULL", "" );
+ print("'str', 0 -> "); test("FULL", nuls );
+ print("'', 'str' -> "); test("", "FULL");
+ print("'', '' -> "); test("", "" );
+ print("'', 0 -> "); test("", nuls );
+ print("0, 'str' -> "); test(nuls, "FULL");
+ print("0, '' -> "); test(nuls, "" );
+ print("0, 0 -> "); test(nuls, nuls );
+}