In programming, when should constants be used?

Using constants in programming is essential for maintaining the integrity of values that should not change during the execution of a program. A constant is a fixed value that, once set, remains the same throughout the program, thereby preventing accidental modification. This can enhance code readability and help prevent bugs, as it becomes clear to anyone reading the code that these specific values are meant to be fixed.

In particular, defining certain values as constants can help convey their purpose, such as maximum limits, configuration settings, or other static values that are critical to the functionality of the software. Since these identifiers are intended to represent values that are definitive and unchangeable, utilizing constants can essentially act as a form of documentation within the code, making it easier for other developers (or even the original developer at a later stage) to understand the program's behavior.

While the other options discuss scenarios that involve frequent changes, data storage, or user input, none of these contexts align with the fundamental purpose of constants, which are specifically designed to represent fixed, unchanging values.