lab 7 completed

code/daniel/python_files/lab07-ccv/lab07-ccv.py

@@ -0,0 +1,112 @@
+# Lab 7: Credit Card Validation
+
+# Let's write a function credit_card_validator which returns whether a string containing a credit card number is valid as a boolean. The steps are as follows:
+
+#     Convert the input string into a list of ints
+#     Slice off the last digit. That is the check digit.
+#     Reverse the digits.
+#     Double every other element in the reversed list (starting with the first number in the list).
+#     Subtract nine from numbers over nine.
+#     Sum all values.
+#     Take the second digit of that sum.
+#     If that matches the check digit, the whole card number is valid.
+
+# Here is a valid credit card number to test with: 4556737586899855
+
+# For example, the worked out steps would be:
+
+#     4 5 5 6 7 3 7 5 8 6 8 9 9 8 5 5
+#     4 5 5 6 7 3 7 5 8 6 8 9 9 8 5
+#     5 8 9 9 8 6 8 5 7 3 7 6 5 5 4
+#     10 8 18 9 16 6 16 5 14 3 14 6 10 5 8
+#     1 8 9 9 7 6 7 5 5 3 5 6 1 5 8
+#     85
+#     5
+#     True Valid!
+# ========================================================================================
+
+
+enter_ccn = (input("Enter your 16-digit credit card number: "))
+# print(len(enter_ccn))
+
+
+try:
+    len(enter_ccn) == 16
+    enter_ccn = list(enter_ccn)
+    print(enter_ccn)
+    # print("check")
+except (ValueError):
+    print("Invalid number length, try again")
+    print(enter_ccn)
+except (ValueError):
+    print('Please enter a number')
+# ====================================================
+# Convert the input string into a list of ints
+# ====================================================
+# print(enter_ccn)
+# print(type(enter_ccn))
+
+# ====================================================
+# Slice off the last digit. That is the check digit.
+# ====================================================
+check_digit = enter_ccn.pop()
+print(check_digit)
+
+# ====================================================
+# Reverse the digits.
+# ====================================================
+enter_ccn.reverse()
+print(enter_ccn)
+
+# =============================================================================================
+# Double every other element in the reversed list (starting with the first number in the list).
+# =============================================================================================
+
+index = 0
+ccn_odd_doubled = []
+for odd in enter_ccn:    
+        if int(enter_ccn[index]) % 2 != 0:
+            ccn_odd_doubled.append(int(enter_ccn[index]) * 2)
+            index += 1
+        else:
+            ccn_odd_doubled.append(int(enter_ccn[index]))
+            index += 1
+print(ccn_odd_doubled)
+
+
+# ====================================================
+# Subtract nine from numbers over nine.
+# ====================================================
+index = 0
+for num in ccn_odd_doubled:
+    if ccn_odd_doubled[index] >= 9:
+        ccn_odd_doubled.pop(index)
+        index += 1
+print(ccn_odd_doubled)
+# ====================================================
+# Sum all values.
+# ====================================================
+index = 0
+sum_ccn = 0
+for num in ccn_odd_doubled:
+    sum_ccn += ccn_odd_doubled[index]
+    index += 1
+print(sum_ccn)
+
+# ====================================================
+# Take the second digit of that sum.
+# ====================================================
+index = 1
+second_digit = list(map(int, str(sum_ccn)))
+# print(str(second_digit))
+print(second_digit[index])
+
+
+# ====================================================
+# If that matches the check digit, the whole card number is valid.
+# ====================================================
+
+if check_digit == second_digit[index]:
+    print("True Valid!")
+else:
+    print("False, check digit not valid")