Which of the following is a data item whose value does not change during run time

Which of the following is a data item whose value does not change during run time?

a. literal constant

b. literal variable

c. named constant

d. variable

The Correct Answer and Explanation is :

The correct answer is c. named constant.

Explanation:

A named constant is a data item whose value remains unchanged during the runtime of a program. It is defined once at the beginning of the program or before it is used, and the value associated with it cannot be altered during the execution of the program.

In many programming languages, named constants are declared using specific keywords (such as const in C/C++ or final in Java) to differentiate them from variables. These constants are often used to represent values that are known at the start of the program and will not need to change, such as the value of pi (3.14159) or the speed of light (299,792,458 m/s). For example, in C++:

const double PI = 3.14159;

In this case, PI is a named constant, and its value cannot be modified later in the program. If a program attempts to change the value of PI, it will result in a compile-time error.

The other options:

• a. literal constant: This refers to a specific value, like 5 or 'a'. These are hardcoded values in the code but don’t represent a named entity. Literal constants are constants because their value doesn’t change, but they aren’t given a name like a named constant.
• b. literal variable: This is a term that doesn’t exist in programming. Variables can hold values that may change during execution, but they are not called “literal variables.” If a value is considered literal, it means it’s directly placed in the code.
• d. variable: A variable is a data item that can change its value during runtime. Unlike constants, the value of a variable can be modified throughout the program, making it different from named constants.

In summary, named constants are explicitly declared as unchangeable, which is what differentiates them from variables and other types of data items.

Let me generate a diagram to visually explain the concept of a named constant.

Here’s the diagram illustrating the concept of a named constant, variable, and literal constant. It visually shows how the named constant (e.g., PI = 3.14159) remains unchanged, while a variable can change, and a literal constant is a fixed value directly placed in the code.

Let me know if you need further clarification!