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Question

I am trying to write a code for a simple store that will load products and prices from a file and load it to dictionary and then be able to use it into the program.. but i am trying not to hard code any of the code values so if the file changes it because un-usable.

my file = test.txt contains

banana:3
apple:4

Here what i tried so far

d = {}
f = open('test.txt', 'r')
for line in f.readlines():
    name,score = line.split(":")
    d[name] = int(score)

print('''
Welcome to my store
What would you like to buy today

[1] banana
[2] apple
[3] orange

''')

menumain = int(input('Enter product number to continue: '))
if menumain == 1:
    value = int(input('how many banana you will buy'))
    new = d[name][0] * value
    print('You ordered',value,'banana(s), Which will cost you',new )
else:
    print('error! wrong menu')

what i need is

 new = d[name][0] * value

is it modify this line so it auto picks the index.. what user selected and from the product name. it use the product's value

in this case index 0 will try to get the value banana which is 3 but it is not working

Im doing this because if i write d['banana'] it will work but if something from the outer file is changed the code will break. So i need something so it works soft-coded

Answer 1

You need a list that maps from numbers to product names. You can do:

product_names = d.keys()
print('''
Welcome to my store
What would you like to buy today

''')
for i, p in enumerate(product_names):
    print ("%d) %s" % (i+1, p))
choice = int(input("Enter product number: "))
if i <= len(product_names):
    name = product_names[i+1]
    value = int(input("How many %s do you want to buy: " % name))
    new = d[name] * value
    print("You ordered %d %s(s), which will cost you %d" % (value, name, new))
else:
    print("That's not a valid product number")

Answer 2

It seems like you don't actually want a dict here at all. You're trying to access "the first item". That implies that you want a list:

lst = {}
f = open('test.txt', 'r')
for line in f.readlines():
    name,score = line.split(":")
    lst.append([name, int(score)])

Now we have a list of pairs, we can get the first one:

lst[0]

… or, if you've asked the user to give you a number:

lst[choice]

Of course that's a [name, score] pair, not just a score. So if you want to get the score, you need another [] :

new = lst[choice][1] * value

Answer 3

Looking for something like this? (Using dict here is not very efficient here)

d = []
f = open('file.txt', 'r')
for line in f.readlines():
    name,score = line.split(":")
    d.append([name,int(score)])

d = sorted(d)

print('''
Welcome to my store
What would you like to buy today

''')

i = 0
for prod in d:
      print("["+str(i+1)+"] "+prod[0])
      i += 1

print("\n")

menumain = int(input('Enter product number to continue: '))
if menumain <= (len(d)-1) and menumain >= 0 :
    prod = d[menumain-1]
    value = int(input('how many '+prod[0]+'(s) you will buy? '))
    print('You ordered '+str(value)+' '+prod[0]+'(s), Which will cost you '+ str(prod[1]*int(value)) )
else:
    print('error! wrong menu')