Time for action – selecting a pony from a List using a for loop

Let's add four pony names to a List. Retrieve and display the number of elements in the List. Then use a for loop to display each pony name, and select one of them:

  1. Modify LearningScript as shown in the next screenshot.
  2. Save the file.
  3. In Unity, click on Play.
    Time for action – selecting a pony from a List using a for loop

What just happened?

The following screenshot shows the number of elements in ponyList, the names of the ponies we added to ponyList, and the pony we were looking for:

What just happened?

The analysis of the code is as follows:

  • The code between lines 8 and 9 with its description:
    List<string> ponyList = new List<string>() {"Princess Cadence", "Fluttershy", "Rainbow Dash", "Rarity"};

    A List named ponyList is declared that will store the string type.

    Four strings are added of the pony names.

  • The code on line 11 with its description is as follows:
    Debug.Log("Number of elements in ponyList: " + ponyList.Count);

    The string Number of elements in ponyList: plus the number of elements used in ponyList is displayed in the Console.

    ponyList.Count is using dot syntax to access the Count property, a variable that stores the number of elements in a List.

    Four names were added to ponyList, so it has four elements to store the string names.

  • The code on line 13 with its description is as follows:
    for(int i = 0; i < ponyList.Count; i++)

    The for loop is created.

    The initializer is simply a declared variable that's assigned a value.

    We declared a variable i of type int, and assigned it the a value of 0. Why?

    The first index number in a List is 0.

    The condition is checked for true before the code block, lines 14 to 19, is allowed to be executed.

    When our for loop first begins, the variable i is equal to 0, and ponyList.Count is equal to 4, therefore 0 is less than 4, which is true. Therefore the for loop code block is allowed to execute.

    The iterator, i++, now adds 1 to i, making i now equal to 1.

    i++ is the same thing as writing i = i + 1, which means that you are taking the value in i and adding 1, then assigning that to i.

    The loop repeats until the condition becomes false.

    After four times through the loop, i is now equal to 4, therefore the condition is now false because i is not less than 4, so the loop is finished.

    Note

    The letter "i" is typically used as the variable name in a for loop. It's tradition. If you happen to have nested for loops, then the variable names used will be the letters j, k, l, and so on, as needed.

  • The code on lines 15 with its description is as follows:
    Debug.Log(ponyList[i]);

    The elements in ponyList are being access using the index number.

    As the for loop is executed for the first time, i is equal to 0, therefore

    ponyList[i] is actually ponyList[0], the element at index 0.

    The element at index 0 is storing Princess Cadence.

    After each iteration through the for loop, 1 is added to i, therefore the next trip through the for loop, i will be 1.

    ponyList[i] will actually be ponyList[1], the next element at index 1.

    The result is all four ponies will be accessed and displayed in the Console.

  • The code on lines 17 with its description is as follows:
    if(ponyList[i] == "Fluttershy")

    During each iteration through the code block, this if statement is checking to see if the name retrieved from ponyList is equal to "Fluttershy".

    When it is, line 18 is executed.

  • The code on lines 18 with its description is as follows:
    Debug.Log("I was looking for " + ponyList[i]);

    The string I was looking for plus the name Fluttershy is displayed in the Console.

Using the while loop

The while loop executes a code block until a specified expression evaluates to false.

A while loop is very similar to a for loop. It's like breaking the for loop into component parts: 

The syntax of a while loop:
initializer
while (condition)
{
  code block
  iterator
}
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