Try

Watch this video to learn about the new concepts shown in the program:

Knowledge organiser

The new commands used in this program and others that may be useful. Select them below to learn more:

int x = Convert.ToInt32(y);

Casts (converts) the string y into a 32-bit integer x. Integers are whole numbers, positive, negative or zero.

double x = Convert.ToDouble(y);

Casts (changes) y into a decimal x. Decimals are also called doubles, floats or real numbers.

string x = Console.ReadLine();

Assigns x to be an input from the keyboard. Print a prompt first with Console.WriteLine(y);.

return x;

Returns the value x from a subprogram so that it can be used elsewhere in the program.

Mathematical operators

+ add

- subtract

* multiply

/ divide

$"..." string interpolation

Embeds variables in output strings. E.g. assuming name = "Dave" and age = 18, the statement

Console.WriteLine($"Hello {name}. You are {age} years old.");

outputs Hello Dave. You are 18 years old.. You can also join strings and variables with +, e.g. "Hello " + name.

Investigate

Questions to think about with this program to check your understanding:

Explain the purpose of the Convert.ToInt32 command used to read the width, length and price.

Reveal answer

Convert.ToInt32 converts the input from the keyboard, which is always text (a “string”), into a whole number (an “integer”) so that it can be used for mathematical calculations. This is known as “casting”.

Explain why a subprogram was used for carpet_cost instead of writing the code directly inside Main.

Reveal answer

Breaking a program down into subprograms is called decomposition. It makes it easier to write different parts of the program a step at a time. It is easier to read the code. It allows a section of code to be reused more easily.

Make

Change the program below so that it:

Includes the cost of an underlay (the soft cushion underneath the carpet). This is calculated as the width multiplied by the length multiplied by £2.

Typical inputs and outputs from the program would be:

Enter the width of the room to nearest meter:
2
Enter the length of the room to nearest meter:
3
Enter the price of the carpet per m2:
2
The total cost is: £ 79.0

🆘 If you're really stuck, use this Parsons code sorting exercise

Complete program

// Carpet cost program

using System;

class Submission
{
---
    // -------------------------
    // Subprograms
    // -------------------------
    static double carpet_cost(int width, int length, double price)
    {
---
        double carpet = width * length * price;
        int underlay = width * length * 2;
---
        int grippers = width + length;
        int fitting = 50;
        return carpet + underlay + grippers + fitting;
---
    }

---
    // -------------------------
    // Main program
    // -------------------------
    public static void Main(string[] args)
    {
---
        Console.WriteLine("Enter the width of the room to nearest meter:");
        int width = Convert.ToInt32(Console.ReadLine());
---
        Console.WriteLine("Enter the length of the room to nearest meter:");
        int length = Convert.ToInt32(Console.ReadLine());
---
        Console.WriteLine("Enter the price of the carpet per m2:");
        double price = Convert.ToDouble(Console.ReadLine());
---
        Console.WriteLine("The total cost is: £ " + carpet_cost(width, length, price));
---
    }
---
}