Introduction to Computers (L02)

* Hardware* Software* Programming Languages* Three Phase of Program Development* Development and Design Steps* Algorithms* Flowchart Introduction to Computers and Programming Dr. Ming Zhang

Basic Hardware Units of a Computer

Central Processing Unit Arithmetic & Logic Unit

Input Control Output

Memory Second Storage Introduction to Computers and Programming Dr. Ming Zhang

Computer Software* Machine Language 11000000 000000000001* Assemble Language ADD 1, 2* High-Level Language Pascal, C, C++* System Software DOS, UNIX* Applications Microsoft Word Introduction to Computers and Programming Dr. Ming Zhang

Programming Languages (1) Operation: Input (get the data)

FORTRAN: READBASIC: INPUT, READ/DATACOBOL: READ, ACCEPTPascal: READ, READLNC: getchar(), gets(), scanf(), sscanf()C++: cin Introduction to Computers and Programming Dr. Ming Zhang

Programming Languages (2) Operation: Output (display the data)

FORTRAN: WRITE, PRINTBASIC: PRINT, PRINT/USINGCOBOL: WRITE, DISPLAYPascal: WRITE, WRITELNC: putchar(), puts(), printf(), sprintf()C++: cout Introduction to Computers and Programming Dr. Ming Zhang

Three Phase of Program DevelopmentProgram Life Cycle Phase

Maintenance(3)

Documentation(2)

Development and Design(1)

Time Introduction to Computers and Programming Dr. Ming Zhang

Development and Design StepsDevelopment & Design Steps

Test & Correct Solution

Code Solution Develop Solution

Analyse Problem Time Introduction to Computers and Programming Dr. Ming Zhang

Algorithms* Definition of AlgorithmAn algorithm is defined as a step-by-step sequence of instructions that must terminate and describes how the data is to be processed to produce the desired outputs

* Question for Developing an AlgorithmIn essence, an algorithm answers the question, What method will you use to solve this problem? Introduction to Computers and Programming Dr. Ming Zhang

Algorithm for Calculating the Average 1Step1: input a, b, and c.

Step2: calculate the average of a, b, and c.

Step 3: display the average.

step 4: stop. Introduction to Computers and Programming Dr. Ming Zhang

Algorithm for Calculating the Average 2Step1: input value and assign value to Ai, i = 1,2, 3, ...n.Step 2: if no more input value, go to step 3, otherwise go to step 1 Step3: calculate the average of Ai, i = 1,2, 3, ...n.Step 4: display the average.Step 5: stop. Introduction to Computers and Programming Dr. Ming Zhang

Flowchart Symbols (1)Symbol Name Description

Terminal Indicates the beginning or end of an algorithm

Input/Output Indicate an Input or Output operation

Process Indicates computation or data manipulation Introduction to Computers and Programming Dr. Ming Zhang

Flowchart Symbols (2)Symbol Name Description Flow Lines Used to connect the flowchart symbols and indicates the logic flow

Decision Indicates a decision point in the program

Loop Indicates the initial, final, and increment values of a loop Introduction to Computers and Programming Dr. Ming Zhang

Flowchart Symbols (3)Symbol Name Description Predefined Indicates a predefined Process Process, as in calling a sorting process

ConnectorIndicates an entry to, or exit from, another part of the flowchart Introduction to Computers and Programming Dr. Ming Zhang

Flowchart for Calculating the Average 1

Start

Input values for a, b, and c

Calculate the average

Display the average

End Introduction to Computers and Programming Dr. Ming Zhang

Flowchart for Calculating the Average 2

Start

Input values for Ai

End of Calculate the averageN input? YDisplay the average

End Introduction to Computers and Programming Dr. Ming Zhang

Calculate the Average of 100 Numbers

Starti = 1 i=i+1 Input values for Ai

Calculate the averageN i=100? YDisplay the average

End Introduction to Computers and Programming Dr. Ming Zhang