Lecture 01 Course Introduction

Computer Science is no more about computers than astronomy is about telescopes.

• Introduction to Programing
• Managing Complexity: Mastering Abstraction; Programing Paradigms

This is a challenging course that will demand a lot from you.

But this will also be a fruitful course that will bring a lot to you.

• Ask for help if you are stuck and make a good effort on all of the homework.

• Do not share code.

Expressions

Description

An expression describes a computation and evaluates to a value.

Types of expressions

• Primitive Expressions: 2(numbers); "hello"(strings); add(names)
• Arithmetic Expressions: 1 + 2; 15 // 3
• Call Expressions: add(3, 4); max(add(2, 3), 5*min(-1, 4))

Evaluating call expressions

1. Evaluate

• evaluate the operator subexpression
• evaluate each operand subexpression

2. Apply

• apply the value of the operator subexpression to the values of the operand subexpression

Values

Description

• Programs manipulate values

• Values represent different types of data

Types of data

• Integers: 2; 44; -3
• Strings:"hello"; "cs61a"
• Floats: 3.14; 4.5; -2.0
• Booleans: True; False

Expressions evaluate to values in one or more steps

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来源： https://blog.csdn.net/qq_51393126/article/details/113195842