Q: How do I store a student's name, age, and grade together?

You can use a record, which in Python is often implemented as a dictionary. For example: student = {'name': 'Alice', 'age': 15, 'grade': 'A'}. This groups related data of different types under one variable. You can access each field using the key: student['name'] returns 'Alice'. Alternatively, you could use a tuple or a custom class, but dictionaries are straightforward for GCSE.

Q: Why do array indices start at 0?

Array indices start at 0 because the index represents an offset from the memory address of the first element. The first element is at offset 0, so its index is 0. This is a convention in most programming languages (C, Java, Python) and makes memory addressing efficient. For example, if an array starts at memory address 100, the element at index 0 is at address 100, index 1 at 104 (if each element is 4 bytes), and so on.

Q: What is the difference between a one-dimensional and a two-dimensional array?

A one-dimensional array is like a list of items, e.g., [1, 2, 3]. A two-dimensional array is like a table with rows and columns, e.g., [[1, 2], [3, 4]] has 2 rows and 2 columns. To access an element in a 2D array, you need two indices: array[row][column]. For example, array[0][1] returns the element in the first row, second column (2). Two-dimensional arrays are useful for representing grids, matrices, or game boards.

Question 1

What is the difference between a float and an integer in Python?

Accepted Answer

An integer (int) is a whole number without a decimal point, like 5 or -3. A float (float) is a number with a decimal point, like 3.14 or -0.5. In Python, dividing two integers using / always returns a float, even if the result is a whole number (e.g., 4/2 = 2.0). You can convert between them using int() and float().

Question 2

How do I declare a one-dimensional array in Python?

Accepted Answer

In Python, you can create a one-dimensional array using a list. For example: my_array = [10, 20, 30, 40]. Lists are dynamic and can hold mixed data types, but for GCSE you'll usually use homogeneous lists. You can access elements using indices: my_array[0] returns 10. To create an empty list, use my_array = [].

Question 3

What is a Boolean data type used for?

Accepted Answer

A Boolean data type can only have two values: True or False. It is used in conditional statements (if, while) to control the flow of a program. For example, you might use a Boolean variable to track whether a user is logged in: is_logged_in = True. Booleans are also the result of comparison operators like ==, >, and <.

Question 4

How do I store a student's name, age, and grade together?

Accepted Answer

You can use a record, which in Python is often implemented as a dictionary. For example: student = {'name': 'Alice', 'age': 15, 'grade': 'A'}. This groups related data of different types under one variable. You can access each field using the key: student['name'] returns 'Alice'. Alternatively, you could use a tuple or a custom class, but dictionaries are straightforward for GCSE.

Question 5

Why do array indices start at 0?

Accepted Answer

Array indices start at 0 because the index represents an offset from the memory address of the first element. The first element is at offset 0, so its index is 0. This is a convention in most programming languages (C, Java, Python) and makes memory addressing efficient. For example, if an array starts at memory address 100, the element at index 0 is at address 100, index 1 at 104 (if each element is 4 bytes), and so on.

Question 6

What is the difference between a one-dimensional and a two-dimensional array?

Accepted Answer

A one-dimensional array is like a list of items, e.g., [1, 2, 3]. A two-dimensional array is like a table with rows and columns, e.g., [[1, 2], [3, 4]] has 2 rows and 2 columns. To access an element in a 2D array, you need two indices: array[row][column]. For example, array[0][1] returns the element in the first row, second column (2). Two-dimensional arrays are useful for representing grids, matrices, or game boards.

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