Overview
This lecture explains how to formulate and use conditions in Scala with comparison operators to evaluate contexts and make decisions in programs.
Writing Conditions in Scala
- Conditions are Boolean expressions that answer a specific question using available data.
- To compare a variable (e.g., age) to a threshold, use operators like > or <.
- Example:
age > 20 evaluates if the user is older than 20, returning true or false.
Comparison Operators in Scala
- Equality is checked with
==, not =, to avoid confusion with assignment.
- Common comparison operators:
== tests equality!= tests inequality ("not equal")< tests less than> tests greater than<= tests less than or equal to>= tests greater than or equal to
- Operators produce Boolean results: true or false.
Modeling Situations with Conditions
- Define relevant variables and thresholds to represent real-world situations as conditions.
- Example 1: Room temperature comfort
- Variable:
temperature
- Condition:
temperature > 14 (comfort if above 14°C)
- Example 2: Car speed monitoring
- Variable:
speed
- Condition:
speed > 50 (car is too fast if speed is above 50 kph)
- Example 3: Store order fulfillment
- Variables:
quantitécomm (quantity ordered), quantitéstock (quantity in stock)
- Condition:
quantitécomm > quantitéstock (cannot fulfill if order exceeds stock)
Key Terms & Definitions
- Boolean expression — An expression that evaluates to true or false.
- Comparison operator — A symbol (e.g., >, ==) used to compare two values.
- Threshold — The reference value against which a variable is compared.
- Assignment operator (=) — Sets a variable’s value.
- Equality operator (==) — Tests if two values are equal.
Action Items / Next Steps
- Practice writing conditions with comparison operators using variables and thresholds.
- Prepare to represent everyday situations as Boolean expressions in Scala.