Chapter01.ppt

Chapter 1: Introduction to Computers and Programming Starting Out with C++ Early Objects Ninth Edition, Global Edition by Tony Gaddis, Judy Walters, and Godfrey Muganda Copyr...

Chapter 1: Introduction to Computers and Programming Starting Out with C++ Early Objects Ninth Edition, Global Edition by Tony Gaddis, Judy Walters, and Godfrey Muganda Copyright © 2017 Pearson Education, Ltd.  Topics 1.1 Why Program? 1.2 Computer Systems: Hardware and Software 1.3 Programs and Programming Languages 1.4 What Is a Program Made of? 1.5 Input, Processing, and Output 1.6 The Programming Process Copyright © 2017 Pearson Education, Ltd. 1-2  1.1 Why Program? Computer – programmable machine designed to follow instructions Program/Software – instructions that a computer follows to perform a task Programmer – person with the right skills who designs, creates, and tests programs for computers SO, without programmers, no programs; without programs, the computer cannot do anything Copyright © 2017 Pearson Education, Ltd. 1-3  Programming – an Art and a Science Artistry in programming: Organization of the tasks that the program performs How information is displayed How the user interacts with the program Science in programming: Understanding of the language used to write the program Understanding how to test the program, and to change it if it does not work as intended Copyright © 2017 Pearson Education, Ltd. 1-4  1.2 Computer Systems: Hardware and Software Hardware – Physical components of a computer Main Hardware Component Categories 1. Central Processing Unit (CPU) 2. Main memory (RAM) 3. Secondary storage devices 4. Input Devices 5. Output Devices Copyright © 2017 Pearson Education, Ltd. 1-5  Main Hardware Component Categories Copyright © 2017 Pearson Education, Ltd. 1-6  Input Devices Used to send information to the computer from outside Many devices can provide input – keyboard, mouse, touch screen, microphone, scanner, digital camera, disk drive, CD/DVD drive, USB flash drive Copyright © 2017 Pearson Education, Ltd. 1-7  Output Devices Used to send information from the computer to the outside Many devices can be used for output – Computer screen, printer, speakers, disk drive, CD/DVD recorder, USB flash drive Copyright © 2017 Pearson Education, Ltd. 1-8  Central Processing Unit (CPU) CPU – Hardware component that runs programs Includes Control Unit – Retrieves and decodes program instructions – Coordinates computer operations Arithmetic & Logic Unit (ALU) – Performs mathematical operations Copyright © 2017 Pearson Education, Ltd. 1-9  The CPU's Role in Running a Program Cycle through: Fetch: get the next program instruction from main memory Decode: interpret the instruction and generate a signal Execute: route the signal to the appropriate component to perform an operation Copyright © 2017 Pearson Education, Ltd. 1-10  Main Memory Holds both program instructions and data Volatile – erased when the program terminates or computer is turned off Also called Random Access Memory (RAM), because the CPU can access data and instructions from any memory location. Copyright © 2017 Pearson Education, Ltd. 1-11  Main Memory Organization Bit – Smallest piece of memory – Stands for binary digit – Hold an electrical charge A positive charge is “on” A negative charge is “off” Byte – Is 8 consecutive bits – Has an address in memory – There are millions (or even billions) of bytes of memory in a computer Copyright © 2017 Pearson Education, Ltd. 1-12  Main Memory Organization Copyright © 2017 Pearson Education, Ltd. 1-13  Secondary Storage Non-volatile / Permanent: Holds data when the program is not running or when the computer is turned off Several forms of secondary storage – disk drive: can be mounted inside the computer or connected to an external port. Data is stored magnetically – optical: CD or DVD drive – flash: USB flash drive Copyright © 2017 Pearson Education, Ltd. 1-14  Software Programs That Run on a Computer System software – programs that manage the computer hardware and the programs that run on the computer – Operating Systems Controls the operation of the computer Manages connected devices and access to storage devices Allows programs to run – Utility Programs Support programs that enhance computer operations Examples: virus scanners, data backup, file compression – Software development tools Used by programmers to create software Examples: compilers, integrated development environments (IDEs) Copyright © 2017 Pearson Education, Ltd. 1-15  Software Programs That Run on a Computer Application Software – programs that make the computer useful for everyday tasks. – Also referred to as “Application software” or “Application Programs”. – Examples: Word Processing, Spreadsheets, Presentations ,email programs, web browsers and games. Copyright © 2017 Pearson Education, Ltd. 1-16  1.3 Programs and Programming Languages Program a set of instructions directing a computer to perform a task Programming Language a special language used to write programs Copyright © 2017 Pearson Education, Ltd. 1-17  Algorithm Algorithm: a set of well-defined steps to perform a task or to solve a problem Order is important. Steps must be performed sequentially Copyright © 2017 Pearson Education, Ltd. 1-18  Programs and Programming Languages Types of languages – Low-level: used for communication with computer hardware directly. Not very easy for a person to read. – High-level: closer to human language Copyright © 2017 Pearson Education, Ltd. 1-19  From a High-level Program to an Executable File a) Create a file containing the program with a text editor. program statements: source code file: source file b) Run the preprocessor to convert source file directives to source code program statements. c) Run the compiler to convert source program statements into machine instructions (machine code), which is stored in an object file. Copyright © 2017 Pearson Education, Ltd. 1-20  From a High-level Program to an Executable File d) Run the linker to connect hardware-specific library code to machine instructions, producing an executable file. Steps b) through d) are often performed by a single command or button click. Errors that occur at any step will prevent the execution of the following steps. Copyright © 2017 Pearson Education, Ltd. 1-21  From a High-level Program to an Executable File Copyright © 2017 Pearson Education, Ltd. 1-22  Putting It All Together There are many software development systems that provide an integrated development environment (IDE). An IDE has the following: text editor compiler debugger other supporting utilities a user interface that ties them all together Copyright © 2017 Pearson Education, Ltd. 1-23  1.4 What Is a Program Made Of? There are common elements in most programming languages 1) Language elements: – Key Words – Programmer-Defined Identifiers – Operators – Punctuation – Syntax Copyright © 2017 Pearson Education, Ltd. 1-24  Example Program #include using namespace std; int main() { double num1 = 5, num2, sum; num2 = 12; sum = num1 + num2; cout