Operators and Expressions in Edexcel A Level Programming | Edexcel A Level 编程中的运算符与表达式

📚 Operators and Expressions in Edexcel A Level Programming | Edexcel A Level 编程中的运算符与表达式

Expressions are the building blocks of every program. In Edexcel A Level Computer Science, you need to combine literals, variables, operators, and function calls to produce values, control flow, and Boolean logic. This article explains the operators you must know, their precedence, and how to evaluate them accurately in exam questions.

表达式是每个程序的基本构造块。在 Edexcel A Level 计算机科学中，你需要组合字面量、变量、运算符和函数调用，以产生值、控制流程和布尔逻辑。本文解释你必须掌握的运算符、它们的优先级，以及如何在考试题中准确求值。

1. Data Types and Literals | 数据类型与字面量

In programming, a literal is a fixed value written directly in the code. The value’s type determines which operations are allowed. Edexcel pseudocode expects you to distinguish clearly between integer, real (float), Boolean, character, and string data types.

在编程中，字面量是直接写在代码中的固定值。值的类型决定了允许哪些运算。Edexcel 伪代码要求你明确区分整数、实数（浮点数）、布尔值、字符和字符串数据类型。

Examples of literals: 42 (integer), 3.14 (real), True (Boolean), 'A' (character), and "hello" (string). Mixing incompatible types without casting can cause errors or unexpected results.

字面量示例：42（整数）、3.14（实数）、True（布尔值）、'A'（字符）和 "hello"（字符串）。不进行类型转换就混合不兼容类型会导致错误或意外结果。

Remember that the character '7' is not the same as the integer 7. The character is a symbol; the integer is a numeric quantity. This distinction is tested in Edexcel programming questions.

记住字符 '7' 与整数 7 不同。字符是符号，整数是数值量

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