3.5 Boolean Expressions 布尔表达式

The way statements are sequenced and combined in a program determines the computed result. Programs incorporate iteration and selection constructs to represent repetition and make decisions to handle varied input values.

• 程序中语句的排序和组合方式决定了计算结果。程序结合迭代和选择结构来表示重复并做出决策来处理各种输入值。

核心要点 Core Points

1. A Boolean value is either true or false.

   • 布尔值要么是真要么是假。

2. The exam reference sheet provides the following relational operators: =, ≠, >, <, ≥, and ≤.

   • 考试参考表提供以下关系运算符：=、≠、>、<、≥和≤。

3. These relational operators are used to test the relationship between two variables, expressions, or values. A comparison using a relational operator evaluates to a Boolean value. For example, a = b evaluates to true if a and b are equal; otherwise, it evaluates to false.

   • 这些关系运算符用于测试两个变量、表达式或值之间的关系。使用关系运算符的比较计算为布尔值。例如，如果a和b相等，a = b计算为真；否则，它计算为假。

4. The exam reference sheet provides the logical operators NOT, AND, and OR, which evaluate to a Boolean value.

   • 考试参考表提供逻辑运算符NOT、AND和OR，它们计算为布尔值。

5. The NOT operator evaluates to true if the condition is false; otherwise it evaluates to false. (Example: NOT (condition))

   • 如果condition是false，NOT运算符计算为true；否则它计算为false。（示例：NOT (condition)）

6. The AND operator evaluates to true if both condition1 and condition2 are true; otherwise it evaluates to false. (Example: condition1 AND condition2)

   • 如果condition1和condition2都是true，AND运算符计算为true；否则它计算为false。（示例：condition1 AND condition2）

7. The OR operator evaluates to true if condition1 is true or if condition2 is true or if both condition1 and condition2 are true; otherwise it evaluates to false. (Example: condition1 OR condition2)

   • 如果condition1是true或condition2是true或condition1和condition2都是true，OR运算符计算为true；否则它计算为false。（示例：condition1 OR condition2）

8. The operand for a logical operator is either a Boolean expression or a single Boolean value.

   • 逻辑运算符的操作数要么是布尔表达式，要么是单个布尔值。

学生活动 Student Activities

1. For relationships between two variables, expressions, or values:

   • 对于两个变量、表达式或值之间的关系：
   • Write expressions using relational operators.
     • 使用关系运算符编写表达式。
   • Evaluate expressions that use relational operators.
     • 计算使用关系运算符的表达式。

2. For relationships between Boolean values:

   • 对于布尔值之间的关系：
   • Write expressions using logical operators.
     • 使用逻辑运算符编写表达式。
   • Evaluate expressions that use logic operators.
     • 计算使用逻辑运算符的表达式。

相关资源 Related Resources

• AP CSP Exam Reference Sheet
  • AP CSP考试参考表