[Dana] Add one correct and one erroneous program (#69)

* A correct IntXor program with input/output files

* An erroneous program with accessing a variable out of scope

---------

Co-authored-by: Kostis Sagonas <kostis@cs.ntua.gr>

Author: AntonisAk

dana/programs-erroneous/scope_error.dana

@@ -0,0 +1,12 @@
+# x is declared in the loop but called outside
+# the loop -> out of scope error
+
+def main
+	var i is int
+	i	:= 10
+	loop:
+		var x is byte
+		x := 'A'
+		i := i - 1
+		if i=0	: break
+	x := 42

dana/programs/IntXor.dana

@@ -0,0 +1,64 @@
+# A (not so efficient) program that returns the XOR of 2 ints 
+
+def main:
+	
+	# A binary number is represented with an array
+	# where every bit is stored as an int
+	
+	# Function definitions
+	def DecToBin: n as int, N as int[15]
+		var max i is int
+		max	:= 16384
+		i	:= 14
+
+		loop:
+			N[i] := n / max
+			n := n % max					
+			max := max / 2
+			i = i - 1
+			if i < 0:	break
+	
+	def BinToDec is int: N as int[15]
+		var max i n is int
+		max := 16384
+		i   := 14
+		n	:= 0
+		
+		loop:
+			n := n + N[i] *  max					
+			max := max / 2
+			i = i - 1
+			if i < 0:	break
+		return n
+
+	def XOR: A B X is int[15]
+		var i is int
+		i := 14
+	
+		loop:
+			X[i] := (A[i] + B[i]) % 2	
+			i = i - 1
+			if i < 0:	break
+
+
+	# Main program
+	var a b x is int
+	var A B X is int[15]
+
+	# Read input
+	writeString: "Input 2 non negative integers"
+	a := readInteger() 
+	b := readInteger()
+
+	# Convert to binary 
+	DecToBin: a, A
+	DecToBin: b, B
+
+	# Calculate XOR
+	XOR: A, B, X
+	
+	# Convert result to int
+	x := BinToDec(X)
+	
+	# Print result
+	writeInteger: x

dana/programs/IntXor.input

@@ -0,0 +1 @@
+10472 31738

dana/programs/IntXor.output

@@ -0,0 +1 @@
+21266