Exercise - Implement the foreach statement

  • 12 minutes

Suppose you work for a manufacturing company. The company needs you to complete an inventory of your warehouse to determine the number of products that are ready to ship. In addition to the total number of finished products, you need to report the number of finished products stored in each individual bin in your warehouse, along with a running total. This running total will be used to create an audit trail so you can double-check your work and identify "shrinkage".

Looping through an array using foreach

The foreach statement provides a simple, clean way to iterate through the elements of an array. The foreach statement processes array elements in increasing index order, starting with index 0 and ending with index Length - 1. It uses a temporary variable to hold the value of the array element associated with the current iteration. Each iteration will run the code block that's located below the foreach declaration.

Here's a simple example:

string[] names = { "Rowena", "Robin", "Bao" };
foreach (string name in names)
{
    Console.WriteLine(name);
}

Below the foreach keyword, the code block that contains the Console.WriteLine(name); will execute once for each element of the names array. As the .NET runtime loops through each element of the array, the value stored in the current element of the names array is assigned to the temporary variable name for easy access inside of the code block.

If you ran the code, you would see the following result.

Rowena
Robin
Bao

Use the foreach statement to create a sum of all the items on hand in each bin of your warehouse.

Create and initialize an array of int

  1. Ensure that you have an empty Program.cs file open in Visual Studio Code.

    If necessary, open Visual Studio Code, and then complete the following steps to prepare a Program.cs file in the Editor:

    1. On the File menu, select Open Folder.

    2. Use the Open Folder dialog to navigate to, and then open, the CsharpProjects folder.

    3. In the Visual Studio Code EXPLORER panel, select Program.cs.

    4. On the Visual Studio Code Selection menu, select Select All, and then press the Delete key.

  2. To create an array of type int that stores the number of finished products in each bin, enter the following code:

    int[] inventory = { 200, 450, 700, 175, 250 };

Add a foreach statement to iterate through the array

  1. To create a foreach statement that iterates through each element of the inventory array, enter the following code:

    foreach (int items in inventory)
{

}

    Notice that the foreach statement temporarily assigns the value of the current array element to an int variable named items.

  2. Ensure that your code matches the following:

    int[] inventory = { 200, 450, 700, 175, 250 };

foreach (int items in inventory)
{

}

Add a variable to sum the value of each element in the array

  1. Position the cursor on the blank code line above the foreach statement.

  2. To declare a new variable that represents the sum of all finished products in your warehouse, enter the following code:

    int sum = 0;

    Ensure that you declare the variable outside of the foreach statement.

  3. Position the cursor inside the code block of the foreach statement.

  4. To add the current value stored in items to the sum variable, enter the following code:

    sum += items;

  5. Ensure your code matches the following:

    int[] inventory = { 200, 450, 700, 175, 250 };
int sum = 0;
foreach (int items in inventory)
{
    sum += items;
}

Display the final value of sum

  1. Create a blank code line below the code block of the foreach statement.

  2. To report the final sum of items in your inventory, enter the following code:

    Console.WriteLine($"We have {sum} items in inventory.");

  3. Ensure that your code matches the following:

    int[] inventory = { 200, 450, 700, 175, 250 };
int sum = 0;
foreach (int items in inventory)
{
    sum += items;
}

Console.WriteLine($"We have {sum} items in inventory.");

  4. On the Visual Studio Code File menu, click Save.

  5. In the EXPLORER panel, to open a Terminal at your TestProject folder location, right-click TestProject, and then select Open in Integrated Terminal.

  6. At the Terminal command prompt, type dotnet run and then press Enter.

    We have 1775 items in inventory.

Create a variable to hold the current bin number and display the running total

To fulfill the final requirement of your inventory reporting project, you'll need to create a variable that will hold the current iteration of the foreach statement so you can display the bin and the count of finished items in that bin, along with the running total of all items of bins accounted for so far.

  1. Create a blank code line above the foreach statement.

  2. To declare int variable named bin that's initialized to 0, enter the following code:

    int bin = 0;

    You will use bin to store the number of the bin whose inventory is currently being processed.

  3. Inside the foreach code block, to increment bin each time the code block is executed, enter the following code:

    bin++;

    Notice that you use the ++ operator to increment the value of the variable by 1. This is a shortcut for bin = bin + 1.

  4. To report the bin number, the number of finished products in the bin, and the running total of finished products, enter the following code inside the foreach code block, after bin++;:

    Console.WriteLine($"Bin {bin} = {items} items (Running total: {sum})");

    This code will use your counter variable bin, the temporary foreach variable items, and your sum variable to report the current state of your inventory in a nicely formatted message.

  5. Ensure that your code matches the following:

    int[] inventory = { 200, 450, 700, 175, 250 };
int sum = 0;
int bin = 0;
foreach (int items in inventory)
{
    sum += items;
    bin++;
    Console.WriteLine($"Bin {bin} = {items} items (Running total: {sum})");
}
Console.WriteLine($"We have {sum} items in inventory.");

  6. Save the changes to your Program.cs file, and then run the application.

    You should see the following output:

    Bin 1 = 200 items (Running total: 200)
Bin 2 = 450 items (Running total: 650)
Bin 3 = 700 items (Running total: 1350)
Bin 4 = 175 items (Running total: 1525)
Bin 5 = 250 items (Running total: 1775)
We have 1775 items in inventory.

Recap

Here's a few things to remember about foreach statements and incrementing values that you learned in this unit:

  • Use the foreach statement to iterate through each element in an array, executing the associated code block once for each element in the array.
  • The foreach statement sets the value of the current element in the array to a temporary variable, which you can use in the body of the code block.
  • Use the ++ increment operator to add 1 to the current value of a variable.