Computer Science - 9210 OxfordAQA

String Handling Operations In A Programming

Overview

A program is handed the text AB-2481 and has to work out that the last four characters are a number, that the hyphen is in the right place, and that the whole thing is seven characters long. None of that is arithmetic and none of it is guesswork. Each step is one of a small set of operations on text, and this specification names seven of them.

This lesson covers all seven: finding the length of a string, finding the position of something inside it, taking a substring out of it, joining strings by concatenation, converting a character to its character code and back again, and the string conversion operations that turn text into numbers and numbers into text. Together they are how a program reads a reference code, splits a name into initials, validates a password and turns keyboard input into something it can add up.

Objectives

  1. Understand and be able to use:
  2. length
  3. position
  4. substring
  5. concatenation
  6. convert character to character code
  7. convert character code to character
  8. string conversion operations.

Mind map

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Lesson Note

A string is a sequence of characters, and a sequence is exactly the kind of thing you can measure, search, cut up and join. The specification lists the operations you must understand and be able to use, and they divide neatly into three groups.

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Lesson Evaluation

Congratulations on completing the lesson on String Handling Operations In A Programming. 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.

  1. What is the length of the string Green Bridge? A. 11 B. 12 C. 13 D. 2 Answer: B
  2. Positions are numbered from 0. What is the value of SUBSTRING("COMPUTER", 2, 3)? A. MPU B. OMP C. MPUT D. COM Answer: A
  3. The character code for A is 65. What is the character code for F? A. 66 B. 69 C. 70 D. 71 Answer: C
  4. Which operation is needed before a value read from a text file can be used in arithmetic? A. Concatenation B. Convert character to character code C. String to integer D. Substring Answer: C
  5. What is the result of the concatenation "7" + "3"? A. 10 B. 21 C. 73 D. 4 Answer: C

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