Question

Identify error(s), if any, in the following array declarations. If a statement is incorrect, provide the correct statement. a. double weights[100]; b. int age[0..80]; c. string students[101]; d. int100 list[]; e. double[50] salaries; f. const double LENGTH = 30.00; double list[LENGTH]; g. const int SIZE = 100; int list[SIZE - 1];

Short answer

Errors: b (`int age[81];`), d (`int list[100];`), e (`double salaries[50];`), f (`const int LENGTH = 30; double list[LENGTH];`).

Step-by-step solution

Analyze declaration (a)

The declaration `double weights[100];` is correct. It declares an array named `weights` with a type of `double` and a valid size of 100.

Analyze declaration (b)

The declaration `int age[0..80];` is incorrect. In C++ syntax, array indices are denoted using square brackets with a single size constant, not a range. The correct statement should be: `int age[81];` to accommodate indices 0 through 80.

Analyze declaration (c)

The declaration `string students[101];` is correct. It creates an array named `students` with type `string` and size 101, which is valid.

Analyze declaration (d)

The declaration `int100 list[];` is incorrect. In C++, specifying an array type with a number directly concatenated to the type keyword is invalid. The correct version should be `int list[100];` where `100` represents the size of the array.

Analyze declaration (e)

The declaration `double[50] salaries;` is incorrect. In C++, the size of the array must be specified within the square brackets immediately following the array name. The correct version should be `double salaries[50];`.

Analyze declaration (f)

The declaration, both `const double LENGTH = 30.00;` and `double list[LENGTH];`, is incorrect because lengths must be integer constants in arrays. Modify LENGTH to int, i.e., `const int LENGTH = 30;` and then `double list[LENGTH];`.

Analyze declaration (g)

The declaration `const int SIZE = 100; int list[SIZE - 1];` is correct. It creates an array `list` of integers with size `99`, correctly using the integer constant `SIZE - 1`.

Key concepts

Array Syntax Errors

Array syntax errors are common pitfalls in C++ programming, especially for beginners. They often occur when the syntax or rules for defining an array are not properly followed. In C++, arrays are a collection of elements of a single type, and they are declared with the syntax: `type name[size];`.
Here are some typical mistakes that lead to syntax errors in array declarations:

• Using incorrect symbols for array indices, such as `int age[0..80]` instead of square brackets with a single number.
• Omitting the type size, for example, `int100 list[];` incorrectly concatenates the size with the type instead of separating them.
• Misplacing the brackets, like in `double[50] salaries;`, where the brackets must come after the variable name.

Understanding these syntax rules helps prevent errors and ensures that arrays are correctly defined.

C++ Programming Concepts

C++ is a powerful programming language that provides numerous features to create efficient and robust programs. Among its features is the ability to declare arrays, which are simple but essential data structures. Arrays in C++ are used to store multiple elements of the same type efficiently. They have fixed sizes, which means once declared, their size cannot be changed.
Here are some fundamental C++ programming concepts related to arrays:

• Data Types: Arrays can be of any data type, like `int`, `double`, `string`, etc.
• Constants: Constants can be used to define array sizes, ensuring that the corresponding size is constant at compile-time.
• Fixed Size: Arrays must have a predefined fixed size, which cannot be adjusted during runtime.

These concepts play crucial roles in efficient memory usage and performance optimization.

Error Correction in C++

One of the crucial skills in C++ programming is identifying and correcting errors, particularly syntax errors that occur during array declarations. Correcting syntax errors involves understanding the nature of the error and applying the right fix based on C++ rules.
For instance, when you encounter an error such as `int age[0..80];`, you must realize that C++ does not support the use of range-based indices and instead should declare the array as `int age[81];`. This not only corrects the syntax but also respects C++ zero-based index position.
To correct C++ errors effectively:

• Always check for correct bracket positions.
• Ensure type and variable names are not concatenated.
• Remember that array sizes should be integer constants.

Following these guidelines helps to correct errors quickly and prevents potential bugs in the program.