Safer way of user input

Author: Karan Goel

Numbers/calc.py

@@ -1,22 +1,24 @@
-# -*- coding: cp1252 -*-
-"""
-Calculator - A simple calculator to do basic operators.
-"""
-
-if __name__ == '__main__':
-    num1 = input("Number 1: ")
-    num2 = input("Number 2: ")
-    op = raw_input("Operation (+, -, /, *): ")
-
-    if op not in '+-/*':
-        print "Invalid operator"
-    else:
-        if op == '+':
-            res = num1 + num2
-        elif op == '-':
-            res = num1 - num2
-        elif op == '/':
-            res = num1 / num2
-        elif op == '*':
-            res = num1 * num2
-        print "%d %s %d = %d" % (num1, op, num2, res)
+"""
+Calculator - A simple calculator to do basic operators.
+"""
+
+if __name__ == '__main__':
+    try:
+        num1 = int(raw_input("Number 1: "))
+        num2 = int(raw_input("Number 2: "))
+    except:
+        print 'Invalid input'
+    else:
+        op = raw_input("Operation (+, -, /, *): ")
+        if op not in '+-/*':
+            print "Invalid operator"
+        else:
+            if op == '+':
+                res = num1 + num2
+            elif op == '-':
+                res = num1 - num2
+            elif op == '/':
+                res = num1 / num2
+            elif op == '*':
+                res = num1 * num2
+            print "%d %s %d = %d" % (num1, op, num2, res)