Accessing Array Elements

In C#, you access elements of an array using the square bracket notation. Remember that array indexing is zero-based. This means that:

• myArray[0] references the first element in the array.
• myArray[2] references the third element in the array.

You can both retrieve and set the value of an element using this notation:

myArray[2] = 9;          // Sets the third element to 9
string[] primates = { "Gorilla", "Ape", "Lemur", "Simian" };
primates[0] = "Baboon";  // Replaces "Gorilla" with "Baboon"

Using Loops to Access Array Elements

Loops are ideal for accessing each element in turn. The following for loop prints each element of the array:

int[] myArray = { 23, 16, 9, 86, 54, 3 };
for (int i = 0; i < myArray.Length; i++)
{
    Console.WriteLine(myArray[i]);  // Print each element
}

• myArray.Length is a property that returns the number of elements in the array. Here, it would return 6.
• The loop runs from i = 0 to i < myArray.Length - 1, ensuring we do not exceed the bounds of the array.

Array Bounds and Exceptions

• Lower Bound: The lowest index of an array is always 0.
• Upper Bound: The highest index is always myArray.Length - 1.
• Out-of-Bounds Access: Trying to access an index outside this range (e.g., myArray[6] or myArray[-1]) will result in an IndexOutOfRangeException. This is an error indicating that you are trying to access a memory location not allocated to the array.

Note

You can use expressions within the square brackets, such as myArray[i + 1] or myArray[12 / 4 - 1], as long as the result is a valid index.

Using the foreach Loop

The foreach loop is a convenient way to iterate through all elements in an array:

int[] myArray = { 23, 16, 9, 86, 54, 3 };
foreach (int element in myArray)
{
    Console.WriteLine(element);  // Print each element
}

• The foreach loop processes each element in the array, from the first to the last.
• The loop variable element is read-only within the loop and represents the current array element.
• This loop is ideal for read-only access but cannot be used to modify the array elements directly.

Additional Tips

• Empty Arrays: An array can be declared with a size of zero, but accessing any element will throw an IndexOutOfRangeException.
• Null Arrays: If an array is not initialized, attempting to access it will result in a NullReferenceException. Always check if an array is initialized before use.