Basics of Programming

Programming Languages and Organization

Interpreted and Compiled Programming Languages

Interpreted programming:

Interpreted programming examples:

Compiled programming:

• Programs that you run on your computer
• Packaged or compiled into one file
• Usually larger programs
• Used to help solve more challenging problems, like interpreting source code

Compiled programming examples:

• C, C++, and C# are used in many OSs, like MS Windows, Apple macOS and Linux
• Java works well across platforms, like the Android OS

Compiled programming:

Comparing Compiled and Interpreted Programming Languages

Choosing a programming language:

Developers determine what programming language is best to use depending on:

• What they are most experienced with and trust
• What is best for their users
• What is the most efficient to use

Programming languages:

Interpreted vs. compiled

Query and Assembly Programming Languages

Programming language levels:

High-level programming languages:

• More sophisticated
• Use common English

• SQL, Pascal, Python

  Low-level programming languages:

• Use simple symbols to represent machine code
• ARM, MIPS, X86

Query languages:

• A query is a request for information from a database
• The database searches its tables for information requested and returns results
• Important that both the user application making the query and the database handling the query are speaking the same language
• Writing a query means using predefined and understandable instructions to make the request to a database
• Achieved using programmatic code (query language/database query language)
• Most prevalent database query language is SQL
• Other query languages available:
  • AQL, CQL, Datalog, and DMX

SQL vs. NoSQL:

• NoSQL (Not Only SQL)
• Key difference is data structures
• SQL databases:
  • Relational
  • Use structured, predefined schemas
• NoSQL databases:
  • Non-relational
  • Dynamic schemas for unstructured data

How does a query language work?

Query language is predominantly used to:

• Request data from a database
• Create, read, update, and delete data in a database (CRUD)
• Database consists of structured tables with multiple row and columns of data

When a user performs a query, the database:

1. retrieve data from the table
2. Arranges data into some sort of order
3. Returns and presents query results

Query statements:

• Database queries are either:
  • Select commands
  • Action commands (CREATE, INSERT, UPDATE)
• More common to use the term “statement”
• Select queries request data from a database

• Action queries manipulate data in a database

  Common query statements:

query statement examples:

Assembly Languages

• Less sophisticated than query languages, structured programming languages, and OOP languages
• Uses simple symbols to represent 0s and 1s
• Closely tied to CPU architecture

• Each CPU type has its own assembly language

  Assembly language syntax:

• Simple readable format
• Entered one line at a time

• One statement per line

  {lable} mnemonic {operand list} ;{comment}
  

  mov TOTAL, 212 ;Transfer the value in the memory variable TOTAL
  

  Assemblers:

• Assembly languages are translated using an assembler instead of a compiler or interpreter
• One statement translates into just one machine code instruction

• Opposite to high-level languages where one statement can be translated into multiple machine code instructions

  Translate using mnemonics:

• Input (INP), Output (OUT), Load (LDA), Store (STA), Add (ADD)

  Statements consist of:

• Opcodes that tell the CPU what to do with data
• Operands that tell the CPU where to find the data

Understanding Code Organization Methods

Pseudocode vs. flowcharts:

Pseudocode	Flowcharts
Informal, high-level algorithm description	Pictorial representation of algorithm, displays steps as boxes and arrows
Step-by-step sequence of solving a problem	Used in designing or documenting a process or program
Bridge to project code, follows logic	Good for smaller concepts and problems
Helps programmers share ideas without extraneous waste of creating code	Provide easy method of communication about logic behind concept
Provides structure that is not dependent on a programming language	Offer good starting point for project

Flowcharts:

• Graphical or pictorial representation of an algorithm
• Symbols, shapes, and arrows in different colors to demo a process or program
• Analyze different methods of solving a problem or completing a process
• Standard symbols to highlight elements and relationships

Flowchart software:

Pseudocode:

Pseudocode Advantages:

• Simply explains each line of code
• Focuses more on logic
• Code development stage is easier
• Word/phrases represent lines of computer operations
• Simplifies translation to code
• Code in different computer languages
• Easier review by development groups
• Translates quickly and easily to any computer language
• More concise, easier to modify
• Easier than developing a flowchart
• Usually less than one page

Programming Logic and Concepts

Branching and Looping Programming Logic

Introduction to programming logic:

Boolean expressions and variables:

Branching programming logic:

Branching statements allow program execution flow:

• if
• if-then-else
• Switch
• GoTo

Looping programming logic:

While loop: Condition is evaluated before processing, if true, then loop is executed

For loop: Initial value performed once, condition tests and compares, if false is returned, loop is stopped

Do-while loop: Condition always executed after the body of a loop

Introduction to Programming Concepts

What are identifiers?

• Software developers use identifiers to reference program components
  • Stored values
  • Methods
  • Interfaces
  • Classes
• Identifiers store two types of data values:
  • Constants
  • Variables

What are containers?

• Special type of identifiers to reference multiple program elements
  • No need to create a variable for every element
  • Faster and more efficient
  • Ex:
    • To store six numerical integers – create six variables
    • To store 1,000+ integers – use a container

• Arrays and vectors

  Arrays:

• Simplest type of container
• Fixed number of elements stored in sequential order, starting at zero
• Declare an array
  • Specify data type (int, bool, str)
  • Specify max number of elements it can contain
• Syntax
  • Data type > array name > array size []

  int my_array[50]
  

Vectors:

• Dynamic size
• Automatically resize as elements are added or removed
  • a.k.a. ‘dynamic arrays’
• Take up more memory space
• Take longer to access as not stored in sequential memory
• Syntax
  • Container type/data type in <>/name of array

vector <int> my_vector;

What are functions?

• Consequence of modular programming software development methodology
  • Multiple modular components
• Structured, stand-alone, reusable code that performs a single specific action

• Some languages refer to them as subroutines, procedures, methods, or modules

  Two types:

• Standard library functions – built-in functions
• User-defined functions – you write yourself

What are objects?

• Objects are key to understanding object-oriented programming (OOP)
• OOP is a programming methodology focused on objects rather than functions
• Objects contain data in the form of properties (attributes) and code in the form of procedures (methods)
• OOP packages methods with data structures
  • Objects operate on their own data structure

Objects in programming

• Consist of states (properties) and behaviors (methods)
• Store properties in fields (variables)
• Expose their behaviors through methods (functions)