C++ FOR ENGINEERS AND SCIENTISTS THIRD EDITION Chapter 1 Preliminaries 1
Objectives 目標 2 In this chapter, you will learn about: Unit analysis 單位分析 Exponential and scientific notations 指數和科學記號 Software development 軟體開發 Algorithms 演算法 Software, hardware, and computer storage 軟硬體和電腦儲存 Common programming errors 常見程式錯誤
Preliminary One: Unit Analysis 單位分析 3 Using consistent and correct units when making computations is crucial 使用一致和正確的單位 Performing a unit analysis 單位分析 Include only the units and conversion factors in an equation 方程式中只用單位和轉換因子 Cancel out corresponding units in the numerator and denominator 消去分子和分母中的相同單位
Preliminary One: Unit Analysis (continued) 4 Engineering and scientific units: 工程和科學單位 English Engineering system and the International System (SI) are commonly used 使用 SI 單位 Apply one conversion factor at a time and cancel units as you go along to avoid multiplying or dividing by the wrong conversion factor 一次只用一個轉換因子 If the final units do not yield the correct resulting units, then the resulting numerical answer must be incorrect 如果最後單位不正確, 那麼答案也不正確
Preliminary One: Unit Analysis (continued) 5 Table 1.1 Commonly Used Physical Quantities
Preliminary One: Unit Analysis (continued) 6 Table 1.1 Commonly Used Physical Quantities (continued)
Preliminary Two: Exponential and Scientific Notations 指數和科學記號 7 Many engineering and scientific applications deal with extremely large and extremely small numbers 處理非常大和非常小的數字 Written in exponential notation to make entering the numbers in a computer program easier 使用指數記號使得輸入方便 Written in scientific notation when performing hand calculations for verification purposes 使用科學記號幫助手算驗證
Preliminary Two: Exponential and 8 Scientific Notations (continued) Examples of exponential and scientific notation: 範例
Using Scientific Notation 使用科學記號 9 Essential in understanding what formulas are to be used and verifying calculations, typically by hand 幫助了解公式和驗證計算 Convenient for evaluating formulas that use very large or very small numbers 便於使用極大和極小數字時 Two basic exponential rules 指數運算規則 Rule 1: 10 n x 10 m = 10 n+m for any values, positive or negative, of n and m 指數相加 Rule 2: 1/10 -n = 10 n for any positive or negative value of n 負指數
Using Scientific Notation 10 (continued) If exponent is positive, it represents the actual number of zeros that follow the 1 如果指數為正, 其值為 1 後所跟 0 的數目 If exponent is negative, it represents one less than the number of zeros after the decimal point and before the 1 如果指數為負, 其絕對值減 1 代表小數點後的 0 的數目 Scientific notation can be used with any decimal number 科學記號可用於任何十進位數字 Not just powers of 10 也不限於 10 的次方
Using Scientific Notation 11 (continued) Common scientific notations have their own symbols 常用符號 Table 1.2 Scientific Notational Symbols
Preliminary Three: Software 12 Development 軟體開發 Computer program: Self-contained set of instructions used to operate a computer to produce a specific result 電腦程式 : 一組用來產生特定結果的指令 Also called software 又稱軟體 Solution developed to solve a particular problem, written in a form that can be executed on a computer Writing a program is almost the last step in a process that determines: 寫程式其實是解決問題的最後一步 The problem to be solved 問題 The method to be used in the solution 解題方法
Preliminary Three: Software 13 Development (continued) Software development procedure: Helps developers understand the problem to be solved and create an effective, appropriate software solution 軟體開發步驟 : 幫助開發者了解問題並產生有效的軟體解答 Software engineering: 軟體工程 Concerned with creating readable, efficient, reliable, and maintainable programs and systems 關注產生可讀 有效 可靠和易維護的程式 Uses software development procedure to achieve this goal 使用軟體開發步驟來達成這個目標
Preliminary Three: Software 14 Development (continued) Figure 1.1 The three phases of program development 程式開發的三個階段
Phase I: Development and Design 15 第一階段 : 開發和設計 Program requirement: request for a program or a statement of a problem 提出程式需求 After a program requirement is received, Phase I begins 收到需求後階段 1 開始 Phase I consists of four steps: 包含四個步驟 Analysis 分析 Design 設計 Coding 寫程式碼 Testing 測試
Phase I: Development and Design 16 (continued) Figure 1.2 The development and design steps 開發和設計的步驟
Phase I: Development and Design 17 (continued) Step 1: Analyze the Problem 分析問題 Determine and understand the output items the program must produce 決定輸出需求 Determine the input items 決定輸入資料 Both items referred to as the problem s input/output (I/O) 以上兩者稱為問題的 I/O
Phase I: Development and Design 18 (continued) Step 2: Develop a Solution 開發解答 Select the exact set of steps, called an algorithm, to be used to solve the problem 選擇演算法以解決問題 Find the solution by a series of refinements 逐步修正 Start with initial solution in the analysis step until you have an acceptable and complete solution 從初步解答開始直到獲得完整解答 Check solution 檢查答案 Refine initial structure until the tasks in the boxes are completely defined 修改初始架構
Phase I: Development and Design 19 (continued) Figure 1.3 A first-level structure diagram 第一層架構圖
Phase I: Development and Design 20 (continued) Step 2: Develop a Solution (continued) 開發解答 Example: a second-level structure diagram for an inventory tracking system with further refinements 存貨追蹤系統的第二層架構圖 Figure 1.4 A second-level structure diagram
Phase I: Development and Design 21 (continued) Step 3: Code the Solution 寫程式碼 Consists of actually writing a C++ program that corresponds to the solution developed in Step 2 寫出第二步中解答的 C++ 程式碼 Program statements should conform to certain welldesigned patterns or structures that have been defined in solution step 程式敘述的架構應與解答步驟相符
Phase I: Development and Design 22 (continued) Step 3: Code the Solution (continued) Program should contain well-defined patterns or structures of the following types: 程式應有定義良好的架構 Sequence 循序 Selection 選擇 Iteration 遞迴運算 Invocation 調用
Phase I: Development and Design 23 (continued) Step 3: Code the Solution (continued) Sequence: Defines the order in which instructions are executed 循序 : 定義指令的執行順序 Selection: Allows a choice between different operations, based on some condition 選擇 : 允許不同動作 Iteration: Allows the same operation to be repeated based on some condition 遞迴運算 : 重複執行 Also called looping or repetition Invocation: Involves invoking a set of statements when needed 調用 : 需要時徵用其他指令組
Phase I: Development and Design 24 (continued) Step 4: Test and Correct the Program 測試和修正程式 Testing: Method to verify correctness and that requirements are met 測試 : 決定正確性 Bug: A program error 臭蟲 : 程式錯誤 Debugging: The process of locating an error, and correcting and verifying the correction 除臭蟲 : 找出並修正程式錯誤 Testing may reveal errors, but does not guarantee the absence of errors 測試可以找出錯誤, 但不保證找到所有錯誤
Phase I: Development and Design 25 (continued) Step 4: Test and Correct the Program (continued) Table 1.3 lists the comparative amount of effort typically expended on each development and design step in large commercial programming projects 下表是各階段所需時間精力 Table 1.3 Effort Expended in Phase I
Phase II: Documentation 製作文件 26 Five main documents for every problem solution: 五種文件 Program description 程式描述 Algorithm development and changes 演算法開發 Well-commented program listing 註解 Sample test runs 簡單測試案例 Users manual 使用手冊
Phase III: Maintenance 維護 27 Maintenance includes: 維護包括 Ongoing correction of newly discovered bugs 持續修正錯誤 Revisions to meet changing user needs 更改以符合使用者需求 Addition of new features 增加功能 Usually the longest phase 通常是最長的階段 May be the primary source of revenue 也許是收入的主要來源 Good documentation vital for effective maintenance 有效維護需要良好的文件
Backup 備份 28 Process of making copies of program code and documentation on a regular basis 定期複製程式碼和文件 Backup copies = insurance against loss or damage 備份是損失的保險 Consider using off-site storage for additional protection 考慮使用異地備份提高保障
Preliminary Four: Algorithms 演算 29 法 Algorithm: 演算法 Step-by-step sequence of instructions that: 逐步的指令 Must terminate 必須有終止 Describe how the data is to be processed to produce the desired output 描述如何處理資料和產生結果
Preliminary Four: Algorithms 30 (continued) Pseudocode: English-like phrases used to describe the steps in an algorithm 擬程式碼 : 像英文的片語用來描述演算法 Formula: Mathematical equations 數學公式 Flowchart: Diagrams with symbols 流程圖
Preliminary Four: Algorithms 31 (continued) Problem: Calculate the sum of all whole numbers from 1 through 100 問題 : 從 1 加到 100 Figure 1.5 Summing the numbers 1 to 100 方法一
Preliminary Four: Algorithms 32 (continued) Figure 1.5 Summing the numbers 1 to 100 (continued) 方法二
Preliminary Four: Algorithms 33 (continued) Figure 1.5 Summing the numbers 1 to 100 (continued) 方法三
Preliminary Four: Algorithms (continued) 34 Figure 1.6 Flowchart symbols 流程圖符號
Preliminary Four: Algorithms 35 (continued) Figure 1.6 Flowchart symbols (continued)
Preliminary Four: Algorithms (continued) 36 Figure 1.7 Flowchart for calculating the average of three numbers 計算三個數字平均值的流程圖
A Closer Look: Software, Hardware, and Computer Storage 進一步看軟體 硬體 37 和電腦儲存 Programming: Process of writing a program, or software 寫程式 Programming language: 程式語言 Set of instructions used to construct a program 構成程式的指令 Comes in a variety of forms and types 有不同的形式
Machine Language 機器語言 38 Only programs that can actually be used to operate a computer 只有程式可用來指揮電腦 Also referred to as executable programs (executables) 又稱可執行程式 Consists of a sequence of instructions composed of binary numbers 一組二進位數字的指令 Contains two parts: an instruction and an address 包含指令和地址兩部分
Assembly Language 組合語言 39 Substitute word-like symbols, such as ADD, SUB, and MUL, for binary opcodes 代入像英文字的符號 Use decimal numbers and labels for memory addresses 使用十進位數字和標籤代表記憶體位址 Example: ADD 1, 2 Assemblers: Translate programs into machine language 組合編譯器
Assembly Language (continued) 40 Figure 1.9 Assembly-language programs must be translated 組合語言必須加以翻譯
Low- and High-Level Languages 低 41 階和高階語言 Low-level languages: Languages that use instructions tied directly to one type of computer 低階語言 : 直接和硬體有關 Examples: machine language, assembly language 例如機器語言和組合語言 High-level languages: Instructions resemble written languages, such as English 高階語言 : 類似英文 Can be run on a variety of computer types 可用於不同電腦 Examples: Visual Basic, C, C++, Java 例如 VB C++ Java C++ for Engineers and Scientists, Second Edition
Low- and High-Level Languages 42 (continued) Source code: The programs written in a high- or lowlevel language 原始碼 ( 高階或低階語言 ) Source code must be translated to machine instructions in one of two ways: 原始碼必須利用以下兩種方式之一翻譯成機器指令 Interpreter: Each statement is translated individually and executed immediately after translation 解譯器 Compiler: All statements are translated and stored as an executable program, or object program; execution occurs later 編譯器 C++ is predominantly a compiled language C++ 主要是編譯 式語言
Low- and High-Level Languages 43 (continued) Large C++ programs may be stored in two or more separate program files due to: 大的 C++ 程式可以分成好幾個檔案因為 Use of previously written code 重複使用舊程式碼 Use of code provided by the compiler 使用編譯器提供的程式碼 Modular design of the program (for reusability of components) 程式的模組化設計 Linker: Combines all of the compiled code required for the program 連結器
Procedural and Object Orientations 44 程序導向和物件導向 Programs can also be classified by their orientation: 程式語言分類 Procedural: Available instructions are used to create self-contained units called procedures 步驟性 Object-oriented: Reusable objects, containing code and data, are manipulated 物件導向性 Object-oriented languages support reusing existing code more easily 物件導向性語言支援重複使用舊程式碼較佳 C++ contains features of both C++ 兩者都是
Procedural and Object Orientations (continued) 45 Figure 1.10 Creating an executable C++ program 產生可執行的 C++ 程式的過程
Application and System Software 46 應用程式和系統程式 Application software: Programs written to perform particular tasks for users 應用軟體 System software: Collection of programs to operate the computer system 系統軟體 System software must be loaded first; called booting the system 必須先載入系統軟體, 稱為 booting Bootstrap loader: A permanent, automatically executed component to start the boot process 開機程式
Application and System Software 47 (continued) Operating system: The set of system programs used to operate and control a computer 作業系統 Also called OS Tasks performed by the OS include: 作業系統的工作包括 Memory management 記憶體管理 Allocation of CPU time 分配 CPU 時間 Control of input and output 管理輸入和輸出 Management of secondary storage devices 管理次要儲存裝置
Application and System Software 48 (continued) Multi-user system: A system that allows more than one user to run programs on the computer simultaneously 多使用者系統 Multitasking system: A system that allows each user to run multiple programs simultaneously 多工系統 Also called multiprogrammed system 多程式系統
The Development of C++ The purpose of most application programs is to process data to produce specific results 多數應用程式的目的是處理資料和產生特定結果 Figure 1.11 Basic procedural operations 49
The Development of C++ 50 (continued) Early procedural languages included: 早期步驟性語言包括 FORTRAN: Formula Translation ALGOL: Algorithmic Language COBOL: Common Business Oriented Language BASIC: Beginners All-purpose Symbolic Instruction Code Pascal C Early object-oriented language: 早期物件導向語言 C++
Computer Hardware 電腦硬體 51 Computer hardware: Components that support the capabilities of the computer 電腦硬體 Figure 1.14 Basic hardware units of a computer
Computer Hardware (continued) 52 Components include: Arithmetic and logic unit (ALU): Performs arithmetic and logic functions 算數邏輯單元 Control unit: Directs and monitors overall operations 控制單元 Memory unit: Stores instructions and data 記憶體單元 Input and output (I/O) unit: Interfaces to peripheral devices 輸出入單元 Secondary storage: Nonvolatile permanent storage such as hard disks 次要儲存
Computer Hardware (continued) 53 Central processing unit (CPU): Also called microprocessor; combines the ALU and control unit on a single chip 中央處理單元
Computer Hardware (continued) 54 Figure 1.15 VLSI chip connections for a desktop computer
Computer Storage 電腦儲存 55 Bit: Smallest unit of data; value of 0 or 1 位元 Byte: Grouping of 8 bits representing a single character 位元組 Character codes: Collection of patterns of 0s and 1s representing characters 字元碼 Examples: ASCII, EBCDIC
Computer Storage (continued) 56 Number codes: Patterns used to store numbers 數字編碼 Twos complement number code: Represents a decimal number as a binary number of 0s and 1s 二的補數 Determine with a value box Figure 1.17 Converting 10001101 to a base 10 number
Computer Storage (continued) 57 Word: Grouping of one or more bytes 一或多個 bytes 稱為 word Facilitates faster and more extensive data access 幫助資料存取 Number of bytes in a word determines the maximum and minimum values that can be stored: 使用 bytes 的個數決定可儲存的最大和最小值 Table 1.4 Word size and Integer Values
Common Programming Errors 常見 58 錯誤 Common errors include: Forgetting to check that all units for numerical values used in a calculation are consistent 忘記檢查單位的一致性 Using an incorrect form of a conversion factor 使用錯誤的轉換因子 Rushing to write and run a program before fully understanding what s required 未了解問題之前急於去寫程式 Not backing up a program 沒有備份 Not understanding that computers respond only to explicitly defined algorithms 不了解電腦只回應定義明確的演算法
Summary 總結 59 To determine correct forms of a conversion factor, perform a unit analysis 使用單位分析 Software: Programs used to operate a computer 軟體 Programming language types: 程式語言種類 Low-level languages 低階語言 Machine language (executable) programs 機器語言 Assembly languages 組合語言 High-level languages 高階語言 Compiler and interpreter languages 編譯和解譯語言
Summary (continued) 60 Software engineering: discipline concerned with creating readable, efficient, reliable, and maintainable programs 軟體工程 Three phases in software development: 軟體開發三階段 Program development and design 程式開發和設計 Documentation 製作文件 Maintenance 維護
Summary (continued) 61 Four steps in program development and design: 程式開發四步驟 Analyze the problem 分析問題 Develop a solution 開發解答 Code the solution 寫程式碼 Test and correct the solution 測試程式 Algorithm: Step-by-step procedure that describes how a task is performed 演算法 Computer program: Self-contained unit of instructions and data used to operate a computer to produce a desired result 電腦程式
Summary (continued) 62 Four fundamental control structures used in coding: 四種基本控制結構 Sequence 循序 Selection 選擇 Iteration 遞迴運算 Invocation 調用