cs110 week one

• Program


  A sequence of steps. Instructions.
• Programs


  • They break a task down into manageable, trivial chunks
  • Every step must be described in detail, and will be completed literally
• What is a program, or algorithm?
• Steps to solve a problem

  1. Step 1

  2. Step 2

  3. Step 3
• Please open socrative.com, and select the room MBOON
• Computer Science


  • CS is about solving problems
  • Sorting, searching, data representation, network protocols, artificial intelligence, algorithm analysis, encryption
• In CS110, you will learn the basics of C++ programming. Programming skills are transferable to other languages.
• Who uses computer programs?

  • Just about everyone
• What do people use computer programs for?

  • Just about every discipline
• Very few people write computer code. And you are about to become one of the few that can!
• Computer


  • A machine for doing math
  • Math with numbers that can mean letters, shapes, colours, sounds
  • Math that can complete algorithms
  • Algorithms that can make decisions, trade stocks, buy a pair of sneakers, play a cat video
• Algorithm


  • A recipe, or a procedure, or step-by-step guide
  • It breaks down a problem into manageable, trivial chunks
  • Coding an algorithm is like teaching a child or an alien how to do something, every step must be described, will be completed literally, to the letter
• Example Algorithms


  • Lift a box
  • Make Cookie Dough
• What steps can a computer perform?


  • Sequence
  • Selection
  • Repetition
  • Subroutine
• Hardware


  The physical components
• Software


  • The instructions (e.g. operating system, applications, etc.)
  • Software can be easily (to some extent) manipulated, which allows the same hardware to be used for multiple purposes
• Hardware Components


  • CPU
  • Memory
  • Storage devices
  • Input devices (Keyboard, Mouse, Microphone)
  • Output devices (Monitor, speakers)
  • Communication devices

  
• Central Processing Unit (CPU)

  Many things affect CPU performance: clock speed, number of cores, cache size, interconnect bandwidth, word length (32-bit vs. 64-bit)
• Random Access Memory (RAM)

  • Short-term storage used for both data and CPU instructions
  • Data stored in RAM is volatile, which means that if power is lost, the data stored is also lost
  • Computers store data in binary format — 1's and 0's. 1 or 0 is one bit. 8 bits is called a byte

  
• Storage Devices


  • Programs and data are permanently stored on storage devices and are moved to RAM when the computer actually uses them
  • Examples: Internal storage: HDD (Hard Disk Drive) and/or SSD (Solid State Drive), External storage: HDD, SSD, Flash drives, DVDs, tape, etc.

  
• Software


  • A set of instructions a computer will follow when the program is executed
  • Computers are stupid, they only do what they are told to do, and they need to be told in a language they understand
• Programming Languages


  • Machine Language
  • Assembly Language
  • High-Level Language
• Machine Language


  • A set of primitive instructions built into every computer
  • Programming with native machine language is a tedious process, the language depends on the CPU you are programming, and the programs are highly difficult to read and modify
• Assembly Language


  • Developed to make programming easier, but still requires a program called assembler to convert assembly language programs into machine code
  • Programs are machine-dependent, so a different program must be written for every machine architecture you want to run it on

  
• High-Level Language


  • English-like and easier to learn and program
  • Largely independent of the computer they are being run on
• Popular High-Level/3G Languages


  • Python
  • JavaScript
  • Java
  • C#
  • C
  • C++
• Fourth and Fifth Generation Languages

  • Fourth generation languages are not general purpose, they have specific and limited capabilities, and are much easier to use if you are new to programming
  • Fifth generation languages are designed to express constraints so that a program can solve the problem — the programmer does not write any algorithms
• Boundary Blurring Languages


  Some 3G languages manage to have many of the user-friendly advantages of 4G languages while remaining general purpose, sometimes these features are part of the core language, and sometimes they require the use of external packages or libraries
• Operating System (OS)


  A program that manages and controls a computer's activities
• Most popular operating systems

  • Windows (10/11)
  • MacOS
  • Linux (Ubuntu)
• Compiled vs. Interpreted Source Code

  • Compiled languages are more efficient/run faster, but require a two-step process to run your code (compile, then run the compiled file)
  • Interpreted languages are slower, but only require a one-step process (run the code)
• Sequence for compiling code

  1. Translates into language the machine can understand

  2. Links the object file with other supporting library code

  
• Basic Control Structures


  • Sequence
  • Selection (branch)
  • Looping/Iteration (repetition)
  • Subroutine
• Sequence


  A series of statements that execute one after another
• Selection (branch)


  Used to determine which of two or more statements to execute, based on certain conditions
• Looping/Iteration (repetition)


  Used to repeat statements while certain conditions are met
• Subroutine


  A smaller part of a program; a collection of these work together to solve the original problem
• Interaction: Input and Output

  A program can interact with the outside world through input (prompting a user for information, collecting information from a sensor) and output (displaying information to the user, sending information to another system)
• Example: Is a Year a Leap Year?

  1. Prompt user for four-digit year

  2. Input Year

  3. Compute YearIsLeapYear

  4. If YearIsLeapYear is true, write "Year is a leap year", otherwise write "Year is not a leap year"
• YearIsLeapYear Algorithm


  1. Divide the year by 4

  2. If the remainder isn't zero, return false (The year is not a leap year)

  3. Otherwise divide the year by 100 and if the remainder isn't 0, return true (The year is a leap year)

  4. Otherwise, divide the year by 400 and if the remainder isn't 0 return false (The year is not a leap year)

  5. Otherwise, return true (year is a leap year)