add while loop

Author: ngdangtuan

calculator.py

@@ -1,6 +1,6 @@
 """
 Written by: Shreyas Daniel - github.com/shreydan
-Description: Uses Pythons eval() function 
+Description: Uses Pythons eval() function
              as a way to implement calculator
 
 Functions available:
@@ -22,41 +22,53 @@
 
 
 def main():
-    
+
     def calc(k):
 
-        functions = ['sin', 'cos', 'tan', 'sqrt', 'pi']    
-        
+        functions = ['sin', 'cos', 'tan', 'sqrt', 'pi']
+
         for i in functions:
             if i in k.lower():
                 withmath = 'math.' + i
                 k = k.replace(i, withmath)
-        
+
         try:
             k = eval(k)
         except ZeroDivisionError:
+
             print("Can't divide by 0")
             exit()
         except NameError:
             print('Invalid input')
             exit()
-        
+
         return k
 
-    print("\nScientific Calculator\nEg: pi * sin(90) - sqrt(81)")
+    def result(k):
+        k = k.replace(' ', '')
+        k = k.replace('^', '**')
+        k = k.replace('=', '')
+        k = k.replace('?', '')
+        k = k.replace('%', '/100')
+
+        print("\n" + str(calc(k)))
+
+    print("\nScientific Calculator\nEg: pi * sin(90) - sqrt(81)\nEnter quit to exit")
 
     if sys.version_info.major >= 3:
-        k = input("\nWhat is ")
+        while True:
+            k = input("\nWhat is ")
+            if k == 'quit':
+                break
+            result(k)
+
     else:
-        k = raw_input("\nWhat is ")
+        while True:
+            k = raw_input("\nWhat is ")
+            if k == 'quit':
+                break
+            result(k)
 
-    k = k.replace(' ', '')
-    k = k.replace('^', '**')
-    k = k.replace('=', '')
-    k = k.replace('?', '')
-    k = k.replace('%', '/100')
 
-    print("\n" + str(calc(k)))
-    
 if __name__ == '__main__':
     main()