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HL Computer Science, Stack - Coggle Diagram

- - - - Public static void main (string args[]){
    - - if x>3:, print("Three"), x=x+1, print("The end")
    - - Method name example: checkGreaterThan(){
    - - end of a statement or line of code
    - - // is used ofr a single line comment Eg: //This is a comment
      - / is used for a multiple lines comment, / this is the end and /* is the start
- - - - output could go to screen, printer and anything els/ets
- - - - LOGICAL, output(A=="Alex" AND B=="Ted"), this will print FALSE as B doesn't store Ted.
- - - - EXAMPLE: AGE=input("Tell me your age:"), AGEIN10=AGE+10 ,output("In 10 years, you will be " + AGEIN10 + " years old!")
    - - //Get the user's age, AGE=input("Tell me your age."), //Check if elligible for HKID, if (AGE<11) then, output("Sorry, you are too young for a HKID card"), end if
    - - While-loop (Condition-Controlled)
        
        PASSWORD="TheBest", USERPASSWORD="", loop while(USERPASSWORD!=PASSWORD), USERPASSWEOD=input("Enter password:"), if (USERPASSWORD==PASSWORD) then, output("welcome back"), else, output("wrong password"), end if, end loop
        
        PASSWORD="TheBest", USERPASSWORD="", loop while(USEPASSWORD!=PASSWORD), USERPASSWORD=input("Enter password: "), if (USERPASSWORD==PASSWORD) then, output("Welcome back!!!"), else, output("Wrong Password! Try Again...", end if,end loop
        
        While Loop means if the conidtion is true, it will activate the while-loop, when the loop is false, the loop will stop.
      - Counter Loop (Counter-Controlled)
        
        EXAMPLE: SUM=0, loop NUMBER from 0 to 5, output (NUMBER), SUM=SUM+NUMBER, output("Sum is "+ SUM), end loop
        
        Always increase by 1
    - - Array is a collection os data that is of the same type
        
        EXAMPLE: STUDENTS=["Alex", "Miriam", "Louisa", "Trista", "Ryan"]
        
        STUDENTS=["Alex", "Miriam", "Louisa", "Trista", "Ryan"], INDEX=0, loop while (INDEX<5), output(STUDENTS[INDEX]), INDEX=INDEX+1, end loop
      - INDEX
        
        output(STUDENTS[1])
        
        Index will store the first index as [0]
      - The size of an array is the number of elements in that array
- - - - Where, when, what, who, why, how
    - - New system rarely come in a vacuum
      - Normally replacement for a less efficient system that come before.
      - The contextin which it will be used is important to be understoo
        
        Context: background, enviroment, framework, settings
      - Impacts
        
        Enviroment
        
        Mental-Emotional
        
        Culture
        
        Social
        
        Technology
    - - Considerations when considering a new system's context
        
        The limitations of the new system
        
        The extent of the new system
- - - - When New start, Old kept running alongside it (data in both system)
        
        Adv: if the new system fails, the old systems runs a bac
        
        Disadv: running two systems is costly in terms of time and mon
        
        Adv: outputs from the two systems can be compared to see if new one is running correctly
    - - The new system is piloted (tested) with a small subset of the organisation (if bugs all fixed it will be run as a New)
        
        Adv: all features are fully trialle
        
        Adv: ; if the new system fails, only a small part of the organisation suffe
        
        Adv:staff who were part of the pilot can train other staff
        
        Disadv: for the subset of users in the pilot group, there is no backup if the new system fails
    - - From Old to New
        
        Adv: minimal time and effort, new system is available immediate
        
        Disadv: if the new system fails, there is no fall back
    - - The new system is introduced in phases as parts of the old system are gradually replaced with the new system
        
        Adv: training of staff can be done in stages
        
        Adv: allows people to get used to the new system
        
        Disadv: if the new system fails, there is no fall back for that part of the system
- - - - As the same piece of software might have different versions, the data created in one version, might not be compatible with another version.
    - - Moving data from a table to a flat file, or from an array to a linked list, might cause a lot of problem
    - - In the UK, 3/5/18 means 3 May 2018, but it means 5 March in the USA
      - The $ might mean US dollars, but could be taken to mean Zimbabwe dollars which use the same symbol but is worth significantly less.
    - - These rules are applied to inputs. If these are different at the destination than at the source, data will be rejected and l
    - - If the actual transfer is interrupted, only part of the data will be at the destination, leading to los
- - - - Users don't like change
      - New systems might omit old features
      - Old system might be faster in certain circumstances
      - People might find it complex
      - Technology perspective, change might liead to incompatibility
      - Might be data loss during migration
      - Can be expensive (money or time)
    - - Plan: Business needs to have a clear and valid reason and mission for the change process
      - Communicate: most important factor in changing anything within a business, small or large
      - Integrate: make sure everyone is happy with the change
      - Evaluate: check if all the change is beneficial to consider the plan for change
- - - - Legacy systems is an old method, technology, computer system, or application program, that may or may not be supported/available for purchase any more.
      - "Famous" lagacy systems
        
        Hardware: Floppy disks, parallel printer cables
        
        Software: Windows XP, movie maker, industry specific software
        
        Computer Systems: Amiga, Commodore 64
    - - Acquisition (takeover, 100%)
      - Merger (combine, 50%50%)
        
        Merger can be VERY tricky
        
        Language differences
        
        Time zone differences
        
        Issues of software compatibility
        
        Workforce cultural differences
- - - - can either buy a program and install it on a particular computer or set of compute
      - Instakk locally, pay once and use it forever, works offline, more expensive
      - update itself
      - no maintenance cost
      - Perdormance aren't an issue for user
      - Example:
        
        Windows operating system
        
        Photoshop
      - Full Features
    - - Saas/cloud
      - can buy/rent/use software that is installed on a computer somewhere on the internet and then use it though a browser or dedicated local applicati
      - on-demand, use a browser ti access and use, pay for the time use it
      - updated by user
      - time consuming maintenance
      - user have the responsibility to maintain performance
      - IT staff
      - Example:
        
        Google Apps
        
        Dropbox
        
        Office 365
      - Limited Features
- - - - ITEMS.push("anything")
        
        Remove
        
        ITEM = ITEMS.pop()
        
        ITEMS.isEmpty()
        
        Output TRUE when there is no item in the stack, output fasle if opposite