Question

Consider the following declaration: double salary[10]; In this declaration, identify the following: a. The array name. b. The array size. c. The data type of each array component. d. The range of values for the index of the array.

Short answer

Array name: `salary`, Size: 10, Data type: `double`, Index range: 0 to 9.

Step-by-step solution

Identifying the Array Name

In the declaration `double salary[10];`, the name of the array is the word that comes right before the square brackets. In this case, the array is named `salary`.

Identifying the Array Size

The size of the array is determined by the number inside the square brackets. In `double salary[10];`, the number within the brackets is `10`, which indicates that the array can hold 10 elements.

Identifying the Data Type

The data type of each element in the array is specified at the beginning of the declaration. Here, `double` indicates that each element of the `salary` array is of the data type double, which means it will store floating-point numbers.

Determining the Index Range

In C++, array indices start at 0 and go up to one less than the size of the array. Therefore, for an array of size 10, the indices range from 0 to 9.

Key concepts

Array Declaration

An array declaration in C++ is essential for creating arrays, which are collections of elements of the same data type. An array is allocated memory whenever it is declared, allowing you to store multiple values under a single variable name. The declaration syntax typically includes three parts: the data type, the array name, and the size of the array enclosed in square brackets. For instance, in the statement `double salary[10];`, `double` is the data type, `salary` is the name of the array, and `10` specifies the number of elements the array can hold.
Declaring an array sets up a fixed amount of space in memory, so if you declare an array with a size of 10, it will always occupy enough space to hold that many elements. Using arrays helps to organize data and makes code more efficient and organized, especially when dealing with large datasets.

Index Range

The index range of an array in C++ is a crucial concept that dictates how you access array elements. In C++, the array indices start at 0 and extend to one less than the total number of elements in the array. This zero-based indexing system means that for an array with a size of 10, such as `double salary[10];`, valid indices are integers from 0 to 9.
Understanding the correct index range prevents common errors such as accessing elements outside the array boundaries, also known as "out-of-bounds" errors. These errors can lead to undefined behavior, including program crashes or data corruption. As a good practice, always ensure your index is within the legal range to avoid unexpected issues. Additionally, using loops to iterate over arrays typically involves conditions checking index limits, i.e., `for(int i = 0; i < arraySize; i++)`. This ensures that each element of the array is properly accessed without exceeding the bounds.

Data Types in C++

Data types in a C++ array declaration define the type of data each element of the array can store. This can be any built-in type like `int`, `char`, `float`, `double`, or even user-defined types such as classes and structures. The data type is mentioned before the array name and is vital for the compiler to allocate suitable memory space for each element.
In the array declaration `double salary[10];`, `double` is the specified data type. This means each element in the `salary` array can store a floating-point number. C++ uses different amounts of memory for different data types, so a `double` will typically need more memory than an `int`. Hence, choosing the appropriate data type during declaration ensures efficient use of memory and allows the storage of the necessary form of data.

Array Size Determination

Determining the size of an array in C++ is about specifying how many elements it can hold, an essential part of its declaration. The size is indicated by the integer value within the square brackets immediately following the array name. This size determines the fixed memory allocated for the array at the time of declaration.
With `double salary[10];`, the number `10` represents the size, meaning the array can store 10 `double` numbers. It's crucial to note that the size of an array is fixed upon declaration and cannot be altered at runtime. For dynamic-sized arrays, other data structures like vectors in C++ Standard Library can be considered. To avoid inefficiencies or memory wastage, always accurately assess how much data needs to be stored before setting array sizes.
Choosing array sizes carefully is essential in programming to ensure efficient use of resources and application performance.