Basics of Programming

Interpreted and Compiled Programming Languages

Programming Languages

• Common programming languages categories:
  • Interpreted
  • Compiled
• Many programming languages are compiled and interpreted
• The developer determines which languages is best suited for the project

Interpreted programming

• Some interpreted programming languages are outdated
• Some are more versatile and easier to learn languages
• Interpreted programming languages need an interpreter to translate the source code
• Translators are built into the browser or require a program on your computer to interpret the code

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

  

Examples

Examples of compiled programming languages are:

• C, C++ and C# are used in many operating systems, like Microsoft. 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 Programming Languages

• Also called script code or scripting, used to automate tasks
• Interpreter programs read and execute the source code line by line
• The source code need to be executed each time
• Runs on almost any OS with the right interpreter

Compiled programming languages

• Also called programming languages
• Used for more complex programs that complete larger tasks
• Larger programs installed on the computer or device
• Longer time to write the code but runs faster
• Grouped into one downloadable file

Interpreted vs. compiled

Programming Language examples

C, C++, C#:

• Compiled programming language

• C is the original language, C++ and C# are variations

• Case sensitive

• Basis for Windows and many operating systems

• Takes more time to learn and use for coding but requires less memory and code runs faster

  Java:

• Compiled programming language

• Case-sensitive, object-oriented programming language

• Requires Java Virtual Machine (JVM) to run the code

• Programming language for Android OS

• Cross-platform language that runs the same code on macOS, Windows and Linux

  Python:

• Interpreted programming language

• Scripting language

• General-use, case-sensitive

• Used with Windows, macOS, and Linux OSes and with server-side web app code

• Requires Python engine to interpret code

  JavaScript:

• Interpreted

• Scripting language that runs on client side web browsers

• Case insensitive

• Simple scripts are run with HTML

• Complex scripts are run in separate files

• Not to be confused with Java, the compiled programming language

  HTML:

• Interpreted

• HyperText Markup Language

• Mostly case-insensitive

• Uses tags to format web pages on client-side web browsers

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 rows and columns of data

  When a user performs a query, the database:

  1. Retrieves data from the table
  2. Arranges data into some sort of order
  3. Returns and prevents 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

• SELECT * FROM suppliers;
• SELECT name FROM suppliers, WHERE name = ‘Mike’;
• CREATE DATABASE products;
• DROP TABLE suppliers;
• ALTER TABLE suppliers;
• DROP COLUMN firstname;
• SELECT AVG(purchases);
• FROM suppliers;

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

{label} mnemonic {operand list} {;comment}
mov TOTAL, 212 ;Transfer the value 212 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

Code organization is important

Planning and organizing software design:

• Enables writing cleaner, more reliable code
• Helps improve code base
• Reduce bugs and errors
• Has a positive impact on program quality
• Provides consistent and logical format while coding

Pseudocode vs. flowcharts

Flowcharts

• Graphical or pictorial representation of an algorithm

• Symbols, shapes, and arrows in different colors to demo a process of program

• Analyze different methods of solving a problem or completing a process

• Standard symbols to highlight elements and relationships

  

  

Flowchart software

• Provides ability to create flowcharts

• Drag functionality

• Easy-to-use interface

• Team collaboration creating flowcharts

  Examples:

• Microsoft Visio

• Lucidchart

• Draw.io

• DrawAnywhere

Pseudocode advantages

• Simply explains each line of code
• Focuses more on logic
• Code development stage is easier
• Words/phrases represent lines of computer operations
• Simplifies translation
• 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

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

There are three basic loop statements:

• 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, Part 1

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

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 > max 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;

Introduction to Programming Concepts, Part 2

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

How functions work

1. Functions take in data as input
2. Then process the data
3. Then return the result as output

Types of functions

• Standard library functions – built-in functions
  • if, else, while, print
• User-defined functions – you write yourself
  • Once a function is written, you can use it over and over
• Blocks of code in a function are identified in different ways
  • Use {}
  • Use begin-end statements
  • Use indentations

Using function

1. Define a function (create)

• Function keyword, unique name, statements

1. Call a function (invoke)

• Specified actions are performed using supplied parameters

2. Declare a function (some programming languages)

• C, C++

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 field (variables)

• Expose their behaviors through methods (functions)