📚 Edexcel A-Level Programming: Core Concepts, Algorithms and Data Structures | Edexcel A-Level 编程：核心概念、算法与数据结构
This revision guide covers the programming knowledge and skills required for the Edexcel A-Level Computer Science specification, including computational thinking, data types, control structures, data structures, algorithms and programming practice.
本复习指南涵盖 Edexcel A-Level 计算机科学课程所要求的编程知识与技能，包括计算思维、数据类型、控制结构、数据结构、算法和编程实践。
1. Programming Paradigms | 编程范式
Edexcel A-Level programming requires understanding of common paradigms. Procedural programming organises code into procedures and functions that operate on data. Object-oriented programming bundles data and behaviour into classes. Event-driven programming responds to user actions such as button clicks.
Edexcel A-Level 编程要求理解常见范式。过程式编程将代码组织为操作数据的过程和函数；面向对象编程把数据和行为封装在类中；事件驱动编程则响应用户操作（如按钮点击）。
Procedural programming focuses on step-by-step instructions and is usually the first style learned. Object-oriented programming is important for large-scale systems because it supports reuse through inheritance and encapsulation. Event-driven programming is common in graphical user interfaces.
过程式编程注重逐步指令，通常是初学风格。面向对象编程对大型系统很重要，因为它通过继承与封装支持复用。事件驱动编程在图形用户界面中很常见。
2. Data Types and Variables | 数据类型与变量
Programmers must choose appropriate data types to model information accurately. The primitive types include integer for whole numbers, real/float for decimals, Boolean for true/false, character for single symbols, and string for sequences of characters.
程序员必须选择合适的数据类型来准确建模信息。原始类型包括：整数表示整数、实数/浮点数表示小数、布尔表示真/假、字符表示单个符号、字符串表示字符序列。
Casting or type conversion changes one type to another, for example int('5') converts the string '5' to the integer 5. Implicit conversion can occur in some languages, but explicit casting is safer in exams.
类型转换将一种类型转换为另一种类型，例如 int('5') 把字符串 '5' 转换为整数 5。有些语言会发生隐式转换，但在考试中显式转换更安全。
Variables should have meaningful names, and constants should be used for fixed values to improve readability and maintainability.
变量应使用有意义的名字，常量应用于固定值，以提高可读性和可维护性。
3. Selection and Iteration | 选择与循环
and switch/case. Conditions use relational operators such as >, <, >=, <=, ==, != and logical operators AND, OR, NOT.
选择结构让程序做出决策。基本形式是 IF...THEN...ELSE 和 switch/case。条件使用关系运算符（>、<、>=、<=、==、!=）和逻辑运算符 AND、OR、NOT。
Iteration repeats a block of code. Count-controlled loops such as FOR execute a known number of times. Condition-controlled loops such as WHILE and REPEAT...UNTIL execute while a condition remains true or until it becomes true.
循环重复执行代码块。计数控制循环（如 FOR）执行已知次数；条件控制循环（如 WHILE、REPEAT...UNTIL）在条件为真时或直到条件为真时执行。
Nested loops are common for 2D arrays or grid-based problems, but the examiner expects careful control of variables to avoid infinite loops.
Published by TutorHao | A-Level 编程 Revision Series | aleveler.com
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