implementing jumping back and forth (ch23)

samples/ch23_if.lox

@@ -0,0 +1,7 @@
+if (true) {
+    print "first is true!";
+}
+
+if (false) {
+    print "second if false!";
+}

samples/ch23_if_else.lox

@@ -0,0 +1,13 @@
+var a = 1;
+
+if (a == 1) {
+    print "first is true!";
+} else {
+    print "first is false!";
+}
+
+if (a == 2) {
+    print "second is false!";
+} else {
+    print "second is false!";
+}

samples/ch23_if_else_logical_operators.lox

@@ -0,0 +1,31 @@
+print "and...";
+
+if (true and true) {
+    print "should show";
+}
+
+if (true and false) {
+    print "should not show";
+}
+
+if (false and true) {
+    print "should not show";
+}
+
+if (false and false) {
+    print "should not show";
+}
+
+print "or...";
+if (true or true) {
+    print "should show";
+}
+if (true or false) {
+    print "should show";
+}
+if (false or true) {
+    print "should show";
+}
+if (false or false) {
+    print "should show";
+}