Question

Suppose that you have the following declaration: \\[ \text { int } \operatorname{list}[10]=\\{8,9,15,12,80\\}; \\] What is stored in each of the components of list.

Short answer

The first five list components are 8, 9, 15, 12, 80, and the last five are 0.

Step-by-step solution

Understand the Array Declaration

The declaration specifies an integer array named `list` with 10 elements. An integer array with 10 elements is configured, which is initially assigned the numbers `{8, 9, 15, 12, 80}`.

Interpret Uninitialized Elements

The array specifies values for only the first 5 elements. In C/C++ programming, if an array's size is larger than the number of initialization values, the rest of the array elements are automatically initialized to 0.

Determine Values for Each Component

Given the initialization: `list[10] = {8, 9, 15, 12, 80};`, the first five elements of `list` will be 8, 9, 15, 12, and 80 respectively. The remaining five elements will be initialized to 0 by default, as the array size is 10.

Key concepts

Array Initialization

In C++, array initialization is a way to define an array with a set of values at the point of its declaration. When you write \[ \text{int list[10] = \{8, 9, 15, 12, 80\};} \]this statement creates an integer array named `list` with 10 elements.
To initialize an array means to assign it specific values right from the start. The values provided within the curly braces (`\{ \}`) are the initial values assigned to the array elements sequentially, starting from the first element.
Here's a simple breakdown:

• The first element of the array gets the first value: 8.
• The second element gets the next value: 9.
• This process continues until the last provided value, 80, is assigned to the fifth element.

This initialization process allows for concise and efficient assignment of the first few values of the array.

Uninitialized Elements

Uninitialized elements in an array refer to those positions within the array that weren't explicitly assigned a value during initialization. In the declaration \[ \text{int list[10] = \{8, 9, 15, 12, 80\};} \]
there are 10 total elements, however, only the first five elements have been initialized with the provided values.
The C++ language takes care of uninitialized elements by automatically assigning them default values, so you don't have to worry about memory junk or undefined behavior for these elements.
This feature allows developers to avoid potential errors and ensures that all array elements are safely initialized. Specifically, this means:

• Elements 6 through 10 in the `list` array are uninitialized with explicit values in the declaration.

When coding, it's a good practice to always make sure your arrays are properly initialized. This keeps your array usage predictable and manageable.

Default Values in Arrays

Default values in arrays are crucial to understand, particularly when you're dealing with arrays that aren't fully initialized with specific values. When it comes to integer arrays in C++, like the one declared as \[ \text{int list[10] = \{8, 9, 15, 12, 80\};} \]C++ will automatically fill any uninitialized elements with a default value of 0. This is a handy feature that helps prevent errors that could arise from accessing elements with garbage values.
In our example array `list`, because only the first five values are explicitly set, the remaining five elements (from index 5 to 9) are given the default value of 0.
Here’s what happens:

• Elements from list[5] to list[9], or more plainly elements 6 through 10 in the array, are each set to 0.

This default behavior is especially useful in large arrays or complex programs, where manually initializing every single element might be impractical or prone to error.