@@ -2,31 +2,34 @@
 #
 # Exercise 1.27
 import sys
+import csv
 
 def portfolio_cost(filename):
-    cost = 0.0
+    total_cost = 0.0
     stock_price = 0.0
     num_of_shares = 0
     f = open(filename, 'rt')
-    headers = next(f)
+    lines = csv.reader(f)
+    headers = next(lines)
 
-    for line in f:
+    for lineno, line in enumerate(lines, start=1):
+        record = dict(zip(headers, line))
         try:
-            stock = line.split(',')
-            num_of_shares = int(stock[1])
-            stock_price = float(stock[2].strip())
-            cost += (num_of_shares * stock_price)
+            nshares = int(record['shares'])
+            price = float(record['price'])
+            total_cost += nshares * price
+        # This catches errors in int() and float() conversions above
         except ValueError:
-            print('Bad line', line)
+            print(f'Row {lineno}: Bad row: {line}')
 
     f.close()
-    return cost
+    return total_cost
 
 
 if len(sys.argv) == 2:
     filename = sys.argv[1]
 else:
-    filename = 'Data/portfolio.csv'
+    filename = 'Data/portfoliodate.csv'
 
 cost = portfolio_cost(filename)
 print('Total cost:', cost)
@@ -10,7 +10,8 @@ def read_portfolio(filename):
         rows = csv.reader(f)
         headers = next(rows)
         for row in rows:
-            holding = {'name': row[0], 'shares': int(row[1]), 'price': float(row[2])}
+            record = dict(zip(headers, row))
+            holding = record
             portfolio.append(holding)
     return portfolio
 
@@ -34,9 +35,9 @@ def make_report(portfolio, prices):
 
     for holding in portfolio:
         name = holding['name']
-        shares = holding['shares']
+        shares = int(holding['shares'])
         price = prices[name]
-        change = price - holding['price']
+        change = price - float(holding['price'])
         updated_portfolio.append((name, shares, price, change))
 
     return updated_portfolio
@@ -54,7 +55,7 @@ def print_report(report):
         print(f'{name:>10s} {shares:>10d} {money:>10s} {change:>10.2f}')
 
 
-portfolio = read_portfolio('Data/portfolio.csv')
+portfolio = read_portfolio('Data/portfoliodate.csv')
 prices = read_prices('Data/prices.csv')
 report = make_report(portfolio, prices)
 print_report(report)