Summary: 3.8.0

  • Conditionals are used to execute code with a boolean expression
    • boolean expression is either true or false

Concept Summary: 3.8.1

  • Block of statements
    • One or more statements enclosed in curly braces
  • Boolean expression
    • A mathematical or logical expression that is either true or false.
  • compound Boolean expressions
    • A Boolean expression with two or more conditions joined by a logical and && or a logical or ||.
  • conditional
    • Used to execute code based on a boolean expression.
  • DeMorgan’s Laws
    • Rules about how to distribute a negation on a complex conditional.
  • logical and
    • Used in compound boolean expressions that are true if both conditions are true.
  • logical or
    • Used in compound boolean expressions that are true if one of the conditions is true.
  • negation
    • turns a true statement false and a false statement true
  • short circuit evaluation
    • A method of evaluation used when a conditional statement can be determined without evaluating the entire statement
    • Used with logical and and logical or
    • a && b && c && d
      • If a == false, the rest of the statement doesn’t need to be evaluated to know the result will be false

Keyword summary: 3.8.2

  • if
    • Used to start a conditional statement
    • followed by a statement/block which is executed if the expression is true
  • else
    • execute a statement/block if the boolean expression in the if was false
  • else if
    • Tests another condition if the first condition evaluated false
    • used in conjunction with if

Common mistakes: 3.8.4

  • Using = instead of == in conditional statements
  • putting a semicolon at the end of an if statement
    • ends the if before you can do anything
  • using two ifs instead of an if and an else or else if
  • Trouble with compound boolean expressions
  • Not understanding || is an inclusive-or
  • Not understanding or applying negation
    • De Morgan’s Laws
  • Not understanding short circuit evaluation