[Dana] Add evenChecker, sumOfDigits and reverseNumber programs

Author: ddimitrakopoulos

dana/programs/evenChecker.dana

@@ -0,0 +1,22 @@
+def main
+
+  def even: n as int, result as ref int
+    if n % 2 == 0:
+      result := 1
+    else:
+      result := 0
+
+  var n is int
+  var res is int
+
+  n := readInteger()
+
+  even: n, res
+
+  writeInteger: n
+  writeString: " is "
+  if res == 0:
+    writeString: "even!"
+  else:
+    writeString: "odd!"
+  writeString: "\n"

dana/programs/reverseNumber.dana

@@ -0,0 +1,21 @@
+def main
+    def reverse_number: n as int, result as ref int
+        var reversed_n is int
+        reversed_n := 0
+        loop:
+            if n > 0:
+                reversed_n := reversed_n * 10 + n % 10
+                n := n / 10
+            else: break
+
+        result := reversed_n
+
+    var n is int
+    var res is int
+
+    n := readInteger()
+    reverse_number: n, res
+
+    writeString: "Reversed number: "
+    writeInteger: res
+    writeString: "\n"

dana/programs/sumOfDigits.dana

@@ -0,0 +1,22 @@
+def main
+    def sum_of_digits: n as int, result as ref int
+        var sum_digits is int
+        sum_digits := 0
+
+        loop:
+            if n > 0:
+                sum_digits := sum_digits + (n % 10)
+                n := n / 10
+            else: break
+
+        result := sum_digits
+
+    var n is int
+    var res is int
+
+    n := readInteger()
+    sum_of_digits: n, res
+
+    writeString: "Sum of digits: "
+    writeInteger: res
+    writeString: "\n"