Exercise - Add suggested donation data

10 minutes

In this step of the development process, you update the code provided in the starter project folder, adding features for "suggested donation" to the application. The starter project.cs file should be open in Visual Studio Code. Return to the previous prepare unit if you need instructions for getting started.

Create the "Suggested Donation" features

The added donation features require you to create suggestedDonation variable, and to expand the ourAnimals array accommodate the new donation data. Also, you need to add the suggested donation amounts for each animal, and implement a default amount when there suggested donation information is missing.

Add support for suggested donation data

You need to create a new variable to hold suggested donations and expand the ourAnimals array to hold the new data.

Notice the code under comment #1 that declares variables used for populating the ourAnimals array for each animal.

You need to declare another string for the suggested donation data.

// #1 the ourAnimals array will store the following: 
string animalSpecies = "";
string animalID = "";
string animalAge = "";
string animalPhysicalDescription = "";
string animalPersonalityDescription = "";
string animalNickname = "";

Create the suggestedDonation variable below the declaration for animalNickname.

The declaration for the suggestedDonation is added with the following code:
```
string suggestedDonation = "";
```
Locate the code to create the ourAnimals array following comment # 3.

The following line of code creates the array:

string[,] ourAnimals = new string[maxPets, 6];

The sizes defining the two dimensions of the array are the maximum number of pets maxPets and the number 6 for the six strings originally defined, but without room for the new suggestedDonation data.
Update ourAnimals array to hold 7 "columns" of data for each animal instead of 6.

The following line shows the updated code:

string[,] ourAnimals = new string[maxPets, 7];

You expanded the ourAnimals array to support the added suggestedDonation data.

Add `suggestedDonation` amounts to the sample data

Take a minute to review case 0: inside the switch statement following comment #4.

The following code that defines sample data for the first pet before the suggestedDonation data is created. It would fit nicely below the animalNickname!

    case 0:
        animalSpecies = "dog";
        animalID = "d1";
        animalAge = "2";
        animalPhysicalDescription = "medium sized cream colored female golden retriever weighing about 45 pounds. housebroken.";
        animalPersonalityDescription = "loves to have her belly rubbed and likes to chase her tail. gives lots of kisses.";
        animalNickname = "lola";
        break;

Insert a suggestedDonation value above the break statement for case 0; through default: with the following values:

Case 0: suggestedDonation = "85.00";
Case 1: suggestedDonation = "49.99";
Case 2: suggestedDonation = "40.00";
Case 3: suggestedDonation = "";
default: suggestedDonation = "";

The following code shows case 0: code with the addition of 'suggestedDonation':

    case 0:
        animalSpecies = "dog";
        animalID = "d1";
        animalAge = "2";
        animalPhysicalDescription = "medium sized cream colored female golden retriever weighing about 45 pounds. housebroken.";
        animalPersonalityDescription = "loves to have her belly rubbed and likes to chase her tail. gives lots of kisses.";
        animalNickname = "lola";
        suggestedDonation = "85.00";
        break;

In your project.cs file, locate the following array populated with the pet data from case statements (it's just before comment # 5):

    ourAnimals[i, 0] = "ID #: " + animalID;
    ourAnimals[i, 1] = "Species: " + animalSpecies;
    ourAnimals[i, 2] = "Age: " + animalAge;
    ourAnimals[i, 3] = "Nickname: " + animalNickname;
    ourAnimals[i, 4] = "Physical description: " + animalPhysicalDescription;
    ourAnimals[i, 5] = "Personality: " + animalPersonalityDescription;

Notice that suggestedDonation data isn't included as part of the sample data starter code for populating the array.

It makes sense to populate the array with a statement like:
```
ourAnimals[i, 6] = "Suggested Donation: "  + suggestedDonation;
```
But, you don't add that code. In the next section, you'll use another approach.

Data validation with `TryParse()`

The variable suggestedDonation is intended to be a numeric value, but is collected and stored as a string. Consider future cases where you have to validate that suggestedDonation represents a decimal, and that you can convert it to a decimal so it's available to use for billing calculations. To avoid errors when users enter numbers in text format, like twenty, you need to use TryParse validation.

Note

The code samples in this exercise are designed based on en-US culture settings, and use a period (.) as the decimal separator. Building and running the code with a culture setting that uses a different decimal separator (such as a comma ,) frequently gives unexpected results or errors. To fix this issue, replace the period decimal separators in the code samples with your local decimal separator (such as ,). Alternatively, to run a program using the en-US culture setting, add: using System.Globalization;to the top of your program. And after any other using statements, add CultureInfo.CurrentCulture = new CultureInfo("en-US");.

Before comment #5, inside the end of the code block, add the code to validate that suggestedDonation can be cast as a decimal.

You add the code that follows:
```
if (!decimal.TryParse(suggestedDonation, out decimalDonation)){
    decimalDonation = 45.00m; // if suggestedDonation NOT a number, default to 45.00
}
```
If the suggestedDonation variable can't be cast as a decimal, then the code assigns a default value decimalDonation = 45.00m;. If the cast is successful, the TryParse populates decimalDonation. Either way, decimalDonation represents a proper decimal.
Ensure that your validation code is in the right place!

The two lines you added should appear in the code as the top two lines of the following code:
```
    if (!decimal.TryParse(suggestedDonation, out decimalDonation)){
        decimalDonation = 45.00m; // if suggestedDonation NOT a number, default to 45.00
    }
}

// #5 display the top-level menu options
```
Note, validation still doesn't work. You can't forget, the need to declare decimalDonation to use it in the code.
Following the comment #2, declare decimalDonation, after string menuSelection = "";:
```
decimal decimalDonation = 0.00m;
```
Finally you're ready to populate suggestedDonation data for each pet.
Just before comment #5, immediately after the TryParse closing bracket } you completed, add the following code:
```
ourAnimals[i, 6] = $"Suggested Donation: {decimalDonation:C2}";
```
You used the decimalDonation version of the suggested donation data. You also used string interpolation and currency formatting in the output.
Take a minute to review how the suggested donation data finally makes it into the ourAnimals array.

The following code populates the ourAnimals array in context of the TryParse():
```
if (!decimal.TryParse(suggestedDonation, out decimalDonation)){
    decimalDonation = 45.00m; // if suggestedDonation NOT a number, default to 45.00
    }
ourAnimals[i, 6] = $"Suggested Donation: {decimalDonation:C2}";
}

// #5 display the top-level menu options
```
Notice that by using the code {decimalDonation:C2} the suggested donation, from decimalDonation, displays with the local currency symbol and two decimal places as directed by the currency formatting :C2.

Review and update where `ourAnimals` array should be used

The addition of the suggestedDonation data created need for further updates. The menu option "1. List all of our current pet information" is missing the added data.

Notice the code under comment #5, for the menu loop within case 1.

The inner loop "for (int j = 0; j < 6; j++)" that prints the pet attributes needs to account for suggestedDonation data added.

Update the inner loop code exit condition. Increased the exit condition by "1," so it becomes j <7. Check that your code matches the code that follows:

case "1":
// list all pet info
for (int i = 0; i < maxPets; i++)
{
    if (ourAnimals[i, 0] != "ID #: ")
    {
        Console.WriteLine();
        for (int j = 0; j < 7; j++) // increased exit condition
        {
            Console.WriteLine(ourAnimals[i, j]);
        }
    }
}

Testing Overview

With several code additions in place, you need to confirm your code works as expected. The two significant test areas are:

The code complies without errors.
Selecting menu option 1 all pet information displays:
- Output includes all of sample pet information, including: ID, species, age, nickname, physical description, and personality description.
- For each pet, the suggested donation displays with a currency symbol and with two decimal places of precision.

Check your work

Build and run to test the code. Use these steps each time you need to test your code.

On the Visual Studio Code File menu, select Save.
In the EXPLORER view, right-click Starter, and then select Open in Integrated Terminal.

A TERMINAL panel should open below the code Editor area.

There are several ways to open Visual Studio Code's integrated terminal. For example, the top menu provides access to the TERMINAL panel from both the View menu and the Terminal menu. Also, keyboard shortcuts that open the TERMINAL panel are a valuable option for increasing your coding efficiency. Each method is acceptable.
Notice that the TERMINAL panel includes a command line prompt, and that the prompt shows the current folder path. For example:
```
C:\Users\someuser\Desktop\GuidedProject\Starter>
```
You can use the TERMINAL panel to run Command Line Interface (CLI) commands, such as dotnet build and dotnet run. The dotnet build command compiles your code and display error and warning messages related to your code syntax.

Important

You need to ensure that terminal command prompt is open to the root of your project workspace. In this case, the root of the project workspace is the Starter folder, where the Starter.csproj and Program.cs files are located. When you run commands in the terminal, the commands try to perform actions using current folder location. If you try to run the dotnet build or dotnet run commands from a folder location that doesn't contain the files, the commands generate error messages.
At the TERMINAL command prompt, to build your project code, enter the following command: dotnet build

After a couple seconds, you should see a message telling you that your build succeeded, and that you have 0 Warnings and 0 Errors.
```
Determining projects to restore...
All projects are up-to-date for restore.
Starter -> C:\Users\someuser\Desktop\GuidedProject\Starter\bin\Debug\net6.0\Starter.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)
```
Note

Use the earlier dotnet build and dotnet run steps each time you need to test your code in the exercises that follow in this module.
If you see Error or Warning messages, you need to fix them before continuing.

Error and Warning messages list the code line where the issue is found. The following message is an example of a Build FAILED error message:

C:\Users\someuser\Desktop\GuidedProject\Starter\Program.cs(53,18): error CS1002: ; expected [C:\Users\someuser\Desktop\GuidedProject\Starter\Starter.csproj]

This message tells you the type of error that was detected and where to find it. In this case, the message tells you that the Program.cs file contains an error - error CS1002: ; expected. The ; expected suggests that you forgot to include a ; at the end of a statement. The Program.cs(53,18) portion of the message tells you the error location, on code line 53, at a position 18 characters in from the left.

A syntax error like this prevents the Build from succeeding (Build FAILED). Some Build messages provide a "Warning" instead of an "Error," which means there's something to be concerned with, but you can try running the program anyway (Build succeeded).

Once you fix the issues and saved your updates, you can run the dotnet build command again. Continue until you have 0 Warning(s) and 0 Error(s).

If you encounter difficulty resolving an issue on your own, examine the Program.cs code in the Final folder included in the download completed during Setup. The Program.cs code in the Final folder represents the conclusion of all exercises in this module, so it includes code that you didn't create yet.

The solution code often looks different than the Program.cs code that you developed to this point in the Guided project. However, you can examine the Program.cs code in Final to help you isolate and fix an issue in your code.

Avoid relying on the solution code while developing your own solution. Remember that you learn from mistakes and that every developer spends time finding and fixing errors.

Test the updated console app, at the TERMINAL command prompt build & run your project code with one command by entering: dotnet run. When the code runs two menu items display.

Enter "1" to test the "display all pets" output
Enter "2" to test the placeholder message "under construction" message

The output for menu item #1 should closely match the following sample:

ID #: d1
Species: dog
Age: 2
Nickname: lola
Physical description: medium sized cream colored female golden retriever weighing about 45 pounds. housebroken.
Personality: loves to have her belly rubbed and likes to chase her tail. gives lots of kisses.
Suggested Donation: $85.00

ID #: d2
Species: dog
Age: 9
Nickname: gus
Physical description: large reddish-brown male golden retriever weighing about 85 pounds. housebroken.
Personality: loves to have his ears rubbed when he greets you at the door, or at any time! loves to lean-in and give doggy hugs.
Suggested Donation: $49.99

ID #: c3
Species: cat
Age: 1
Nickname: snow
Physical description: small white female weighing about 8 pounds. litter box trained.
Personality: friendly
Suggested Donation: $40.00

ID #: c4
Species: cat
Age:
Nickname: lion
Physical description:
Personality:
Suggested Donation: $45.00

If everything worked as expected, congratulations! Otherwise, look for the error by checking code instruction steps involved. If needed, start over with a new starter Project.cs file and if you still have issues check the solution folder code for this exercise.

Type exit, at the app menu, to end the program and then close the terminal panel.

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