Scripting Classroomnotes 02/Dec/2022

Scripting vs Programming

• Scripting
  • We directly execute code and code is interpreted line by line
  • We use scripting to automate or build small utilities
• Programming
  • Program needs to be compiled.
  • We tend to solve problems/build applications

Scripting/Programming Basics Contd

• Execution of script/program happens line by line
• Consider the following problem
  • user gives you url as input, you need to print the domain name
  • user should be shown error if the input is not in https or http url format
• Solution:
  1. Remember input provided as url url = 'https://qt.com/test'
  2. is url in the http url format and remember as result
  3. print domain if result is true
  4. enter the url in the right format if the result is false
• THis script will have two possibities in its execution
  • 1,2,3
  • 1,2,4
• Generally the above way is referred as conditional execution.
• Consider the following problem
  • user enters number and you need to print all the numbers below that number till 0
• Solution:
  1. Remember input provide as number
  2. Start from index = 0
  3. print index
  4. add 1 to the index
  5. check if it is less than number and remeber as result
  6. if result is true
  7. go to step 3
  8. else stop
• The above approach is called as looping constructs

Character Introduction

• ELSA
  
• What she knows ?
  • Rememebering values
  • + - * / %
  • =
  • <=, >=, ==
• You can instruct her what has to be done in steps and she can do it faster and also repeat this multiple times.

Instruction Manual with ELSA

• Examples 1: Calculate GST (7%)

1. Remember input provided as price
2. calculate price * 7 / 100 and remember as gst
3. say gst

• Examples 2: Calculate electricity assuming till 300 units the bill will be zero any thing above 300 price per unit is 7 rs

1. Rember input provided as units
2. units = units - 300
3. if units < 0 
4.    units = 0
5. say units * 7