Programming

• Programming is used generally to build applications & Scripting to automate the workflow
• Applications:
  • Command line applications
  • Desktop Applications
  • Mobile Applications
  • Web applications
• Technologies used to Develop
  • Command Line Application:
    • java, C, C++, Python, C#, node js …
    • bash or powershell
  • Desktop Applications:
    • C#, node js, python…
  • Mobile Applications:
    • Kotlin
    • Swift
    • react native (java script frameworks)
  • Web Applications:
    • java, Python, C#, node js …
    • angular, react, vue
    • HTML, CSS, Javascript
• How does program run ?
  • Operating systems create process
  • Application will be single process or multiple processes
  • Each process has a unique id (PID) and it gets cpu and memory
  • memory stores the necessary data for application
  • cpu is executing the instructions
  • Options:
    • Compiler: Programs are converted into instructions which OS understands
    • Interpretor: Programs are translate while execution.
    • Hybrid

How to write programs ?

• Approach: Find out more in classroom recording
  
  
  

Problem 1:

• Lisa knows how to add numbers
• instruction format

add 3 & 5

• Make her multiply 5 * 5
• Solution: Represent the problem
  • add 5 + 5 + 5 + 5 + 5

Probem 2:

• Lisa knows how to
  • multiplication
  • division
  • remainder
  • addition
• Example: Sum the number plate
• 432 => 4 + 3 + 2 => 9
• 164 => 1 + 6 + 4 => 11 => 1 + 1 => 2
• Problem: my number number is 414
  • 414 % 10 => 4
  • 414 /10 => 41
  • 41 % 10 => 1
  • 41 /10 = 4
  • 4 % 10 = 4

Understanding memory allocations

• Allocating memory requires specifying size and generally we get a memory address
• Programming languages use data types where we indirectly specify sizes
• to access memory locations we take help of references (Variables or constants)

int i = 10;
string name = "hello" ;

• We have needs for memory sizes
  • fixed size: these are referred as mutable types
  • variable size: new memory has to be allocated for every change.
• Programming Languages: Support two types
  • Automatic memory cleaning (Garbage collection)
  • Manual memory cleaning
• Static Typed Languages and Dynamically Typed Languages
  • In Static typed languages (C, C++, Java, C#) we need to specify type for every memory allocation and in dynamically typed languages (python, javascript, bash) type is decided based on value passed to it