6.0 KiB
Currency Exchange
Welcome to Currency Exchange on Exercism's Python Track.
If you need help running the tests or submitting your code, check out HELP.md
.
If you get stuck on the exercise, check out HINTS.md
, but try and solve it without using those first :)
Introduction
Numbers
There are three different kinds of built-in numbers in Python : ints
, floats
, and complex
. However, in this exercise you'll be dealing only with ints
and floats
.
ints
ints
are whole numbers. e.g. 1234
, -10
, 20201278
.
Integers in Python have arbitrary precision -- the amount of digits is limited only by the available memory of the host system.
floats
floats
are numbers containing a decimal point. e.g. 0.0
,3.14
,-9.01
.
Floating point numbers are usually implemented in Python using a double
in C (15 decimal places of precision), but will vary in representation based on the host system and other implementation details. This can create some surprises when working with floats, but is "good enough" for most situations.
You can see more details and discussions in the following resources:
- Python numeric type documentation
- The Python Tutorial
- Documentation for
int()
built in - Documentation for
float()
built in - 0.30000000000000004.com
Arithmetic
Python fully supports arithmetic between ints
and floats
. It will convert narrower numbers to match their less narrow counterparts when used with the binary arithmetic operators (+
, -
, *
, /
, //
, and %
). When division with /
, //
returns the quotient and %
returns the remainder.
Python considers ints
narrower than floats
. So, using a float in an expression ensures the result will be a float too. However, when doing division, the result will always be a float, even if only integers are used.
# The int is widened to a float here, and a float type is returned.
>>> 3 + 4.0
7.0
>>> 3 * 4.0
12.0
>>> 3 - 2.0
1.0
# Division always returns a float.
>>> 6 / 2
3.0
>>> 7 / 4
1.75
# Calculating remainders.
>>> 7 % 4
3
>>> 2 % 4
2
>>> 12.75 % 3
0.75
If an int result is needed, you can use //
to truncate the result.
>>> 6 // 2
3
>>> 7 // 4
1
To convert a float to an integer, you can use int()
. Also, to convert an integer to a float, you can use float()
.
>>> int(6 / 2)
3
>>> float(1 + 2)
3.0
Instructions
Your friend Chandler plans to visit exotic countries all around the world. Sadly, Chandler's math skills aren't good. He's pretty worried about being scammed by currency exchanges during his trip - and he wants you to make a currency calculator for him. Here are his specifications for the app:
1. Estimate value after exchange
Create the exchange_money()
function, taking 2 parameters:
budget
: The amount of money you are planning to exchange.exchange_rate
: Unit value of the foreign currency.
This function should return the value of the exchanged currency.
Note: If your currency is USD and you want to exchange USD for EUR with an exchange rate of 1.20
, then 1.20 USD == 1 EUR
.
>>> exchange_money(127.5, 1.2)
106.25
2. Calculate currency left after an exchange
Create the get_change()
function, taking 2 parameters:
budget
: Amount of money before exchange.exchanging_value
: Amount of money that is taken from the budget to be exchanged.
This function should return the amount of money that is left from the budget.
>>> get_change(127.5, 120)
7.5
3. Calculate value of bills
Create the get_value_of_bills()
function, taking 2 parameters:
denomination
: The value of a single bill.number_of_bills
: Amount of bills you received.
This function should return the total value of the given bills.
>>> get_value_of_bills(5, 128)
640
4. Calculate number of bills
Create the get_number_of_bills()
function, taking budget
and denomination
.
This function should return the number of bills that you can get using the budget. **Note: ** You can only receive whole bills, not fractions of bills, so remember to divide accordingly.
>>> get_number_of_bills(127.5, 5)
25
5. Calculate value after exchange
Create the exchangeable_value()
function, taking budget
, exchange_rate
, spread
, and denomination
.
Parameter spread
is the percentage taken as an exchange fee.
If 1.00 EUR == 1.20 USD
and the spread is 10
, the actual exchange will be: 1.00 EUR == 1.32 USD
.
This function should return the maximum value of the new currency after calculating the exchange rate plus the spread. Remember that the currency denomination is a whole number, and cannot be sub-divided.
Note: Returned value should be int
type.
>>> exchangeable_value(127.25, 1.20, 10, 20)
80
>>> exchangeable_value(127.25, 1.20, 10, 5)
95
6. Calculate non-exchangeable value
Create the non_exchangeable_value()
function, taking budget
, exchange_rate
, spread
, and denomination
.
This function should return the value that is not exchangeable due to the denomination of the bills.
Note: Returned value should be int
type.
>>> non_exchangeable_value(127.25, 1.20, 10, 20)
16
>>> non_exchangeable_value(127.25, 1.20, 10, 5)
1
Source
Created by
- @Ticktakto
- @Yabby1997
- @limm-jk
- @OMEGA-Y
- @wnstj2007
- @J08K