0905. Training JS #7: if..else and ternary operator

In JavaScript, if..else is the most basic condition statement, it consists of three parts:condition, statement1, statement2, like this:

if condition: statementa
else:         statementb

It means that if the condition is true, then execute the statementa, otherwise execute the statementb.If the statementa or statementb more than one line, you need to add { and } at the head and tail of statement in JS, to keep the same indentation on Python and to put a end in Ruby where it indeed ends.

An example, if we want to judge whether a number is odd or even, we can write code like this:

def odd_even(n):
    if n%2: return "odd number"
    else:   return "even number"

If there is more than one condition to judge, we can use the compound if...else statement. an example:

def old_young(age):
    if age<16:        return "children"
    elif (age<50): return "young man" #use "else if" if needed
    else:             return "old man"

This function returns a different value depending on the parameter age.

Looks very complicated? Well, JS and Ruby also support the ternary operator and Python has something similar too:

statementa if condition else statementb

Condition and statement separated by "?", different statement separated by ":" in both Ruby and JS; in Python you put the condition in the middle of two alternatives. The two examples above can be simplified with ternary operator:

def odd_even(n):
    return "odd number" if n%2 else "even number"
def old_young(age):
    return "children" if age<16 else "young man" if age<50 else "old man"

Task:

Complete function saleHotdogs/SaleHotDogs/sale_hotdogs, function accept 1 parameters:n, n is the number of customers to buy hotdogs, different numbers have different prices (refer to the following table), return a number that the customer need to pay how much money.

number	price (cents)
n < 5	100
n >= 5 and n < 10	95
n >= 10	90

Solution:

def get_price(func):
    def wrapper(number: int):
        price = (number < 5 and 100) or (number >= 10 and 90) or 95
        return func(number, price)
    return wrapper

@get_price
def sale_hotdogs(number: int, price: int) -> int:
    return number * price