Question

Consider the following declaration: double passwords [100] 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: passwords; Size: 100; Data type: double; Index range: 0 to 99.

Step-by-step solution

Identify the Array Name

The array name is the identifier used to refer to the array in your code. In this case, the array name is `passwords`.

Determine the Array Size

The array size is the total number of elements that the array can hold, which is specified inside the brackets. Here, the array can hold 100 elements.

Establish the Data Type of Array Components

Each component of the array has a specific data type. In this declaration, the data type of each array component is `double`, which means each element of the array is a double precision floating-point number.

Identify the Range of Values for the Array Index

The index of an array in most programming languages starts from 0 and goes up to one less than the size of the array. Therefore, for an array of size 100, the index range is from 0 to 99.

Key concepts

Array Name

When working with arrays in C++, the array name is the first critical concept to understand. The array name acts like a label for a group of elements that are stored in a contiguous block of memory. This allows you to perform operations on the array as a whole simply by referring to its name. In the given exercise, the array name is "passwords".
This is similar to how a variable name works, allowing you to access and manipulate the data stored inside. It is crucial because it becomes your primary point of interaction with the array in a program. Use the array name sparingly in large operations and loops to manage data efficiently.

Array Size

The array size determines how many elements can be stored within the array. It is defined inside the square brackets `[]` during the array declaration. Knowing the array size helps ensure you do not exceed the boundaries during operations, which can cause runtime errors in your program. For instance, the array size in this exercise is 100, meaning the array "passwords" can hold up to 100 double values.
An array size should be chosen based on the amount of data you expect to manage. If an array is declared too small, it limits data handling; too large, and it unnecessarily occupies memory. A constant variable can sometimes indicate array size, allowing flexibility if the size needs changing in multiple places in the code.

Data Type

Every element in a C++ array shares the same data type, which impacts the kind of values the array can store. In the provided example, the data type is `double`, indicating that the array holds double precision floating-point numbers. This is important for determining the nature of operations that can be carried out on the array elements.
The choice of data type influences memory usage and precision. For instance, using `double` occupies more memory than `int`, but it provides the capability to store decimal points. This is handy for calculations requiring precision—like financial figures or scientific computations. Proper selection of the data type ensures that the array can efficiently meet the program's needs.

Array Index Range

Array index range in C++ defines which positions within the array are accessible. Indexing starts at 0 and goes up to one less than the array size. This is a common point of confusion since people often expect numbers to start from 1. For an array of size 100, like "passwords", the index range is 0 to 99.

• Start Index: 0
• End Index: Size of array - 1

This zero-based indexing is crucial because accessing an element outside this range (negative or beyond 99) results in undefined behavior, which can lead to bugs or crashes in the program.
When looping through or accessing elements, always ensure indices stay within this range to prevent errors and maintain code safety.