Operators, Expressions and Precedence in Programming | 编程中的运算符、表达式与优先级

📚 Operators, Expressions and Precedence in Programming | 编程中的运算符、表达式与优先级

In Edexcel A-Level Computer Science, understanding operators and how expressions are evaluated is essential for writing correct pseudocode and for tracing algorithms. This article covers the operators you need to know, their precedence, and common exam-style pitfalls.

在 Edexcel A-Level 计算机科学中，理解运算符以及表达式如何求值，对于编写正确的伪代码和追踪算法至关重要。本文介绍你需要掌握的运算符、它们的优先级以及考试中常见的易错点。

1. Operators as Building Blocks | 运算符是构建模块

Operators are special symbols or keywords that tell the computer to perform a specific operation on one or more values. In A-Level programming, you must be able to use arithmetic, relational, Boolean, string, and assignment operators in pseudocode and in a chosen high-level language.

运算符是告诉计算机对一个或多个值执行特定操作的特殊符号或关键字。在 A-Level 编程中，你必须能够在伪代码和所选高级语言中使用算术、关系、布尔、字符串和赋值运算符。

• Arithmetic operators – perform calculations. | 算术运算符 – 执行计算。
• Relational operators – compare values. | 关系运算符 – 比较值。
• Boolean operators – combine truth values. | 布尔运算符 – 组合真值。
• String operators – manipulate text. | 字符串运算符 – 处理文本。
• Assignment operators – store values. | 赋值运算符 – 存储值。

Understanding how these operators interact in an expression is a core skill for tracing and writing algorithms.

理解这些运算符在表达式中如何相互作用，是追踪和编写算法的核心技能。

2. Arithmetic Operators | 算术运算符

Arithmetic operators are used for mathematical calculations. In Edexcel pseudocode, the usual symbols are +, -, *, /, DIV and MOD. DIV returns the whole-number quotient, while MOD returns the remainder after whole-number division.

算术运算符用于数学计算。在 Edexcel 伪代码中，常用符号是 +、-、*、/、DIV 和 MOD。DIV 返回整数商，而 MOD 返回整数除法后的余数。