Exam-style question
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Explain two differences between a variable and a constant in a programming language. Include one suitable example of each.
Model answer
What a good answer should say
- A variable is a named value that may be changed while the program runs.
- For example, in Python, score = 0 could later be followed by score = 10.
- A constant is a named value intended not to change while the program runs.
- For example, in C#, const int MAX_TRIES = 3; declares a named constant.
Explanation
Why this works
The key distinction is whether the value is expected to change. The examples show a variable being assigned a new value and a C# constant being declared with the const keyword.
A complete answer should explain both the changing nature of a variable and the fixed intended nature of a constant.
Common mistake
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