Question

Describe the difference in the meaning of int \(a[5] ;\) and the meaning of \(a[4] .\) What is the meaning of the [5] and [4] in each case?

Short answer

Based on the given step-by-step solution, the short answer is: The expression `int a[5];` declares an array named `a` with a size of 5, which can hold integer elements. The `[5]` in this expression specifies the size of the array. On the other hand, the expression `a[4]` refers to accessing the element at the 4th index in the array `a`. In this case, `[4]` is an index representing the position of the specified element within the array.

Step-by-step solution

Understanding Arrays in C++

In C++, an array is a collection of elements of the same data type, such as integers, floats, or characters. Each element in an array is identified by an index which starts from 0. So, when we declare an array, we must specify its length, i.e., the total number of elements it can hold.

Declare an Array in C++

The syntax for declaring an array in C++ is: `datatype arrayName[arraySize];`, where `datatype` is the type of the array elements, `arrayName` is the name of the array, and `arraySize` is the number of elements in the array. Let's analyze the given expression: `int a[5];`. Here, the datatype is `int`, the array's name is `a` and the array size is 5. This means that the array `a` can hold a maximum of 5 integer elements.

Explain the meaning of `int a[5];`

The expression `int a[5];` is a declaration statement that creates an array of integers named `a` with a size of 5. In this case, the `[5]` is specifying how many elements the array can hold. The memory allocation for the array will be static, and it can store 5 integer values at indices 0, 1, 2, 3, and 4.

Array Indexing in C++

An array element can be accessed using its index, which is specified inside a pair of square brackets `[]`. The index starts from 0, so the first element is at index 0, the second element is at index 1, and so on. Keep in mind that the maximum valid index for the given array `a` is `4`, as there are 5 elements in total.

Explain the meaning of `a[4]`

The expression `a[4]` refers to the element at the 4th index in the array `a`. In this case, `[4]` is an index representing the position of the specified element in the array. So, `a[4]` represents the last element in the array `a`.

Conclusion

To sum up, the expression `int a[5];` declares an array called `a` of integer type with a size of 5 elements, where `[5]` specifies the size of the array. In contrast, the expression `a[4]` refers to accessing the last element in the array `a`, with `[4]` being an index specifying the position of that element in the array.