math2220 Lecture1

Math2220 Lecture 1

Computer and Computer programs

OR "Hardware of Software
Hardware consists of the physical components of the system.
Software consists of programs that control the hardware to solve a problem,

Elements of Hardware

Central Processing Unit(CPU)
Memory (including RAM)
Input/Output Device(keyboard, mouse, monitor, printer, etc etc)

Software

Programs are written using an unambigous computer langauge

Low level: assembly language, machine
High level: C++, java

Math2220 will mainly deal with software written in C++

Software Development

Problem specification(information and goals)
Design(data structure, algorithms)
Implementation(coding)
Building(compiling and linking)
Testing/debugging
Maintenance

Example:

Question: Calculate the increase percentage of the tuition fee.

Problem specification

What do you know? (this year's tuition fee, last year's tuition fee)
What do you want? (the increase percentage)

Design and Implementation

Data Structures
Algorithms(unambiguous directions that use the data structure to solve the problem)
Consists of translating pseudocode into a computer language

Pseudocode for the example

Input this year's tuition fee
Input last year's tuition fee
calculate the increase precentage by the formula

output the result

Here is the code

#include<iostream>
using namespace std;

void main() {
    double thisYearFee, lastYearFee, percentage;
   
    cout << "Please enter last year's tuition fee: ";
    cin >> lastYearFee;
    cout << "Please enter this year's tuition fee: ";
    cin >> thisYearFee;

    percentage = (thisYearFee - lastYearFee)/lastYearFee;

    cout << "The tuition increases " << percentage*100 << "%.\n";
    
    char line[100];
    cin.getline(line,100);
    cin.getline(line,100);

}

Here is the output of the program

Please enter last year's tuition fee: 42310 Please enter this year's tuition fee: 45678 The tuition increases 7.96029%.

Building(Compiling and linking)

Compiling translate high-level code to a langauge the computer understands
Likings adds in the tools used, but didn't define(e.g. cout)

Testing/Debugging, Maintenance, and Documentation

On first attemps roughly 99.9999999% of all codes have mistakes
Can be syntax and logical
Maintenance keeps things up-to-date
Documentation ensures others can use your program

Compiler and Syntax Error

You can think of the compiler as a very strict English teacher. If you make any typographical errors or use any errant punctuation, you will be told about this in no uncertain terms.
Syntax errors: these are where the compiler expects a particular set of symbols and you provide something that is not expected.

For example, in the above program, instead of

double thisYearFee, lastYearFee, percentage;

You type

doule thisYearFee, lastYearFee, percentage;

Then there will be an error message.

Explanation of the program

#include<iostream>     /_____________ these two lines are
included


using namespace std;   \
              so that the libaries
about input/output

 
                   

 
               are available to the program

void main() {

    

               <----------------- fill your codes
here




}

Code	Explanation
`double thisYearFee, lastYearFee, percentage;`	declare 3 decimal numbers
`cout << "Please enter last year's tuition fee: ";`	cout <<"blah blah blah"; outputs blah blah blah on the screen
`cin >> lastYearFee;`	cin >> x; asks the user to input a value. The value will be stored in a variable named x.