Question 1

Why should I use a constant if I can just use a variable?

Accepted Answer

Using a constant for a value that should not change makes your code safer and more readable. It prevents accidental changes to the value elsewhere in the program. It also makes maintenance easier; if a value like a tax rate changes, you only need to update it in one place (the constant declaration) rather than searching for it throughout your code.

Question 2

What is the difference between a `CHAR` and a `STRING` of length 1?

Accepted Answer

Conceptually, a `CHAR` is for a single character, like 'A', while a `STRING` is for a sequence of characters, like "Hello". A `STRING` can have a length of 1, e.g., "A". In many programming languages and in exam pseudocode, they are treated differently. A `CHAR` variable cannot hold a `STRING` value, and vice-versa. Always choose the type that best represents the data's purpose.

Question 3

Do I have to declare variables at the very top of my program?

Accepted Answer

In Cambridge pseudocode, it is standard practice and highly recommended to declare all variables and constants at the beginning of the program or sub-program. This improves readability and helps you plan your program structure before you start writing the logic. Sticking to this convention will earn you marks for clarity and good programming practice.

Question 4

Can I store a number like '123' in a STRING variable?

Accepted Answer

Yes, you can. `MyString <- "123"` is a valid assignment. However, the value is stored as text, not as a number. You cannot perform mathematical calculations on it directly (e.g., `"123" + 1` is an error). You would need to convert the string to an integer first. This is why choosing the correct data type is so important.

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