exercism/cpp/freelancer-rates

Freelancer Rates

Welcome to Freelancer Rates on Exercism's C++ 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

The built-in number types in C++ can be divided into integers and floating points. Integers are whole numbers like 0, 691, or -2. Floating point numbers are numbers with a decimal point like 6.02214076, 0.1, or -1.616.

Integers

The following example shows the declaration and initialization of four different variables

int m_morales{9241};              // base 10: 0-9
int a_apaec{0x24CD};              // base 16: 0-9 and A-F
int m_gargan{0b10010000011001};   // base  2: 0-1
int b_reilly{022031};             // base  8: 0-7
                                  // Leading with a 0 not the letter o.

When you assign a value to an int variable, you can do so directly with a literal. A literal is a hard-coded number like 9241. There are different integer literals for several bases of the representation. Decimal integer literals are the most common and use the digits 0 to 9. By adding a special prefix, like 0x, it is possible to use other bases. The example above shows the number 9421 in its four representations and prefixes. All variables are initialized to the same value.

For more details on the different representation systems, take a look at a small tutorial.

You can use an apostrophe to separate digits for easier readability. 9'241 is the same as 0b0100'100'0001'1001 or 92'4'1.

Floating-Point Numbers

The floating-point literals come in two flavors. In addition to the intuitive 0.0024 it is possible to use its scientific notation 2.4e-3. The most common floating-point type is double.

Arithmetic

C++ supports +, -, *, /, ( and ) and % to form expressions. The result from the operation between two integers is also an integer. 5 / 2 will return 2. When one of the involved types is a floating-point type, the result will also be of a floating-point. 5.0 / 2 and 5 / 2.0 will return 2.5. % is the remainder operator and will return the remainder of an integer division: 5%3 is 2.

Assignment operator

The assignment operator assigns a variable with a literal. Always takes place from right to left, and never the other way around.

int length = 5;
int width = 2;
length = width;

Here integer value 5 is assigned to the variable length. Then integer value 2 is assigned to variable width. Finally value of width is copied to the variable length and the earlier value 5 will be lost. Consider also that we are only assigning the value of width to length at the moment of the assignment operation. Therefore, if the value of width changes at a later moment, it will not affect the value taken by length.

Assignment operator can be combined with the other operators(arithmetic & bitwise) known as compound assignment operators +=, -=, *=, /=, %=. These operators modifies the current value of a variable by performing an operation on it.

// we start with 0 people
int people{};
// we need 0 eggs
int eggs{}; 
// two people joined:
people += 2; 
// people is now 2
// let's add 3 eggs per person
eggs += 3 * people;
// eggs is now 6

Variables people & eggs are initialized to 0. Then, we add integer value 2 over the existing value 0 of the variable people and assign it back to people. people becomes 2 now. Later, we add 3 eggs for each person, which turns out to be 6 eggs in total. Now add this 6 to existing value 0 of the variable eggs and assign it back to eggs. eggs will be 6 now. The equivalent expression would be people = people + 2 and eggs = eggs + (3 * people).

Instructions

In this exercise, you'll be writing code to help a freelancer communicate with a project manager. Your task is to provide a few utilities to quickly calculate daily and monthly rates, optionally with a given discount.

We first establish a few rules between the freelancer and the project manager:

• The daily rate is 8 times the hourly rate.
• A month has 22 billable days.

Sometimes, the freelancer is offering to apply a discount on their daily rate (for example for their most loyal customers or not-for-profit customers).

Discounts are modeled as fractional numbers representing percentages, for example, 25.0 (25%).

1. Calculate the daily rate given an hourly rate

Implement a function called daily_rate to calculate the daily rate given an hourly rate as a parameter. The contract defines that a day has 8 billable hours.

daily_rate(60)
// => 480.0

The returned daily rate should be of type double.

2. Calculate a discounted price

Implement a function apply_discount to calculates the price after a discount. It should accept two parameters: the original price and the discount rate in percent.

apply_discount(150, 10)
// => 135.0

The returned value should always be of type double, not rounded in any way.

3. Calculate the monthly rate, given an hourly rate and a discount

Implement a monthly_rate function to calculate the discounted monthly rate. It should have two parameters, an hourly rate and the discount in percent.

monthly_rate(77, 10.5)
// => 12130

The returned monthly rate should be rounded up (take the ceiling) to the nearest integer.

4. Calculate the number of complete workdays given a budget, hourly rate, and discount

Implement a function days_in_budget that takes a budget, an hourly rate, and a discount, and calculates how many complete days of work that covers.

days_in_budget(20'000, 80, 11.0)
// => 35

The returned number of days should be rounded down (take the floor) to the next integer.

Source

Created by

• @vaeng