Data Types And Structures
Overview
A program is only as good as the way it stores its data. Cram everything into the wrong shape, a whole class of exam scores squeezed into one string, or a student's details spread across five unrelated variables, and even a correct algorithm becomes painful to write and easy to break. Choosing the right data type and the right data structure is a design decision, not an afterthought.
This lesson covers Python's core data types, the three data structures named in the specification, records, one-dimensional arrays and two-dimensional arrays, how to manipulate strings, and the difference between local and global variables when writing subprograms. As throughout this subject, every example is written in Python, one of the three languages, alongside C# and Java, permitted for the Paper 2 practical exam.
Objectives
- Understand the need for, and understand how to use, data types (integer, real, Boolean, char, string)
- Understand the need for, and understand how to use, data structures (records, one-dimensional arrays, two-dimensional arrays)
- Understand the need for, and how to manipulate, strings
- Understand the need for, and how to use, variables and constants
- Understand the need for, and how to use, global and local variables when implementing subprograms
Mind map
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Flashcards
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Data Types And Structures. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Which Python type is the equivalent of the specification's 'char' data type? A) A list of one item B) A string of length 1 C) A single integer D) A Boolean Answer: B
- Which data structure groups several related fields, possibly of different types, under one name? A) A record B) A one-dimensional array C) A constant D) A two-dimensional array Answer: A
- In Python, grid[1][2] accesses which part of a two-dimensional array called grid? A) The first row, third column B) The second row, third column C) The third row, second column D) The whole second row Answer: B
- What keyword must be used inside a function to change the value of a variable defined outside every function? A) local B) const C) global D) static Answer: C
- A function receives a list as a parameter and appends a new item to it. What effect does this have on the original list in the calling code? A) No effect, lists are always copied B) The original list is also updated, since both refer to the same list C) A syntax error occurs D) Only the function's local copy is updated Answer: B
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