Computer-Science-A-level-Ocr
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3-3-networks8 主题
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3-2-databases7 主题
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3-1-compression-encryption-and-hashing4 主题
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2-5-object-oriented-languages7 主题
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2-4-types-of-programming-language4 主题
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2-3-software-development5 主题
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2-2-applications-generation6 主题
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2-1-systems-software8 主题
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1-3-input-output-and-storage2 主题
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1-2-types-of-processor3 主题
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1-1-structure-and-function-of-the-processor1 主题
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structuring-your-responses3 主题
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the-exam-papers2 主题
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8-2-algorithms-for-the-main-data-structures4 主题
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8-1-algorithms10 主题
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7-2-computational-methods11 主题
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7-1-programming-techniques14 主题
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capturing-selecting-managing-and-exchanging-data
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entity-relationship-diagrams
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data-normalisation
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relational-databases
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hashing
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symmetric-vs-asymmetric-encryption
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run-length-encoding-and-dictionary-coding
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lossy-and-lossless-compression
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polymorphism-oop
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encapsulation-oop
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inheritance-oop
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attributes-oop
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methods-oop
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objects-oop
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capturing-selecting-managing-and-exchanging-data
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6-5-thinking-concurrently2 主题
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6-4-thinking-logically2 主题
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6-3-thinking-procedurally3 主题
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6-2-thinking-ahead1 主题
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6-1-thinking-abstractly3 主题
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5-2-moral-and-ethical-issues9 主题
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5-1-computing-related-legislation4 主题
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4-3-boolean-algebra5 主题
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4-2-data-structures10 主题
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4-1-data-types9 主题
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3-4-web-technologies16 主题
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environmental-effects
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automated-decision-making
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computers-in-the-workforce
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layout-colour-paradigms-and-character-sets
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piracy-and-offensive-communications
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analysing-personal-information
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monitoring-behaviour
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censorship-and-the-internet
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artificial-intelligence
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the-regulation-of-investigatory-powers-act-2000
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the-copyright-design-and-patents-act-1988
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the-computer-misuse-act-1990
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the-data-protection-act-1998
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adder-circuits
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flip-flop-circuits
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simplifying-boolean-algebra
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environmental-effects
strings-in-javascript
Strings in JavaScript
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A string is a sequence of characters enclosed in single quotes (
') or double quotes (") -
Strings are widely used for representing and manipulating text-based data
Creating strings
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Strings can be created in JavaScript by enclosing text within quotes:
const message = 'Hello, world!';const name = "John Doe";
String length
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To find the length of a string, use the
lengthproperty -
The
lengthproperty returns the number of characters in a string:
const message = 'Hello, world!';console.log(message.length);
// Output: 13
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In this example, the
lengthproperty is used to determine the number of characters in themessagestring
Substring extraction
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To extract a portion of a string, use the
substring()method -
The
substring()method takes two parameters: the starting index and the ending index (optional) -
A new string is returned containing the characters within the specified range:
const message = 'Hello, world!';const substring = message.substring(0, 5);console.log(substring);
// Output: Hello
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In this example, the
substring()method is used to extract the characters from index 0 to index 5 (exclusive) from themessagestring, resulting in the substring'Hello' -
By omitting the second parameter, the
substring()method will extract the characters from the starting index to the end of the string:
const message = 'Hello, world!';const substring = message.substring(7);console.log(substring);
// Output: world!
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Here, the
substring()method extracts the characters from index 7 to the end of themessagestring, resulting in the substring'world!'
Examiner Tips and Tricks
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JavaScript allows flexibility in choosing single or double quotes to define strings, as long as you maintain consistency within a string
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There are many other things you can do with strings in JavaScript but these are the only ones you need to know before the exam
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The exam might give you additional string functionality but if it does it will provide the code and explain it
Responses