notes.md

Week 04 Day 5

Topics

• statements
  • conditionals
    • if-else
    • if-elseif-else
    • switch case
    • ternary operators
  • iterative statements
• assigments
• challenges

Statements

• Expression - gives or returns o/p or gets i/p
• evaluation of expression is an statement
• two types of statements

1. Conditional Statemetns

• conditional - used to jump /skiparound in a code based on certain conditions

Flow Charts

• flow charts that is, visual representation of how program goes/runs, step by step

• notice every type of box represent different stuff

  

• these are helpful to devise logical solutions of complex problems, that is algorithms

• syntax

  if (condition) {
      // if true do this
  }
  else {
      // do this
  }

• 👉 code snippet

  var pocketMoney = prompt("enter your pocket money ");
  var iceCream = 40;
  
  if (pocketMoney < 40) {
    console.log("no ice cream")
  } else {
    console.log("have some ice cream")
  }

• bear in mind in js it is preferred to use camelCase, it's a convention

• concatenation - joining two strings together

  firstName = "rahul";
  lastName = "_choudhary";
  fullName = firstName + lastName; // output - rahul_choudhary

• parseInt

  var pocketMoney_1 = prompt("enter money ");
  
  // Check if num is valid
  var isNotValid = isNaN(pocketMoney_1);
  
  if (isNotValid) {
      alert("invalid num");
  } else {
  alert("you have valid money");
  }

• use else if to introduce multiple conditions

Nesting of Statements

• condition inside condition, external and internal, it can go upto many levels

Switch Case

• selects code block to execute based on condition, always use break to avoid running all conditions

• syntax

  switch(expression) {
  case x:
    // code block
    break;
  case y:
    // code block
    break;
  default:
    // code block
  }

Ternary Operator

• short hand to write if else conditiional statements

  // condition ? exprIfTrue : exprIfFalse;

2. Iterative Statements

• iterative statements are used to repeat same code block again and again, as and when required

• two types

  • entry check - for loop (fig below), while loop

  

  • entry check loops - check before getting inside loop body, may not even run once

  • exit check - do while

  • syntax

    for (conditions) {
      // do this
    }

  • while loop

  while (i < 10) {
  text += "The number is " + i;
  i++;
  }

• exit check - check after getting inside the loop body, always runs once

• do while

  var text = "";
  var i = 0;
  do {
    text += "The number is " + i;
    i++;
  }
  while (i < 5);

Terms

• keyword - reserved previously by programming language
• algorithms - step by step
• block - pair of opening/closing curly braces is called code block
• NaN - used for error validation

---