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Scala | Decision Making

In Scala, as in most programming languages, you have constructs for decision-making that allow the execution of code blocks based on certain conditions. The most common constructs are if, if-else, and match (equivalent to the switch statement in some other languages).

1. `if` Statement

The simplest form of decision-making is the if statement.

val age = 20
if (age >= 18) {
  println("You are eligible to vote.")
}

2. `if-else` Statement

For branching decisions, you can use if-else.

val age = 15
if (age >= 18) {
  println("You are eligible to vote.")
} else {
  println("You are not eligible to vote.")
}

3. `if-else-if` Ladder

For multiple conditions, you can use the if-else-if ladder.

val score = 85
if (score >= 90) {
  println("Grade: A")
} else if (score >= 80) {
  println("Grade: B")
} else if (score >= 70) {
  println("Grade: C")
} else {
  println("Grade: F")
}

4. `if` Expression

In Scala, if can also be an expression that returns a value.

val age = 20
val eligibility = if (age >= 18) "eligible" else "not eligible"
println(s"You are $eligibility to vote.")

5. `match` Expression

Scala's match expression is a more powerful decision-making tool, similar to the switch statement in other languages but more expressive.

val day = "Monday"
val activity = day match {
  case "Sunday" => "Relax"
  case "Saturday" => "Go out"
  case _ => "Work"   // _ is a wildcard, similar to 'default' in a switch statement
}
println(s"On $day, I will $activity.")

With match, you can also perform pattern matching on various types, like tuples, lists, case classes, etc., making it a versatile tool for decision-making and de-structuring data.

In Conclusion

Decision-making constructs in Scala are both powerful and flexible. They allow for elegant and concise code while preserving the expressiveness required for complex logic.

If-Else Statements in Scala:

Use if-else for basic decision-making.

val x = 10
if (x > 5) {
  println("x is greater than 5")
} else {
  println("x is not greater than 5")
}

Pattern Matching in Scala for Decision Making:

Pattern matching offers a powerful way to make decisions based on data patterns.

val dayOfWeek = "Monday"
dayOfWeek match {
  case "Monday" => println("Start of the week")
  case "Friday" => println("End of the week")
  case _ => println("Some other day")
}

Using match Expression in Scala:

The match expression is a concise form of pattern matching.

val number = 3
val result = number match {
  case 1 => "One"
  case 2 => "Two"
  case _ => "Other"
}

Nested Decision-Making in Scala:

Nest if-else or match expressions for complex decisions.

val x = 10
val y = 5
if (x > 5) {
  if (y > 3) {
    println("Nested condition satisfied")
  }
}

Guard Clauses in Scala Decision Making:

Use guard clauses to add conditions to pattern matching.

val number = 10
number match {
  case x if x > 5 => println("Greater than 5")
  case x if x <= 5 => println("Less than or equal to 5")
}

Boolean Expressions and Decision Making in Scala:
Boolean expressions can be used directly in decision-making.
```
val x = 10
val y = 5
if (x > 5 && y > 3) {
  println("Both conditions satisfied")
}
```

Multiple Conditions with case in Scala Pattern Matching:

Use | to match multiple patterns.

val day = "Saturday"
day match {
  case "Saturday" | "Sunday" => println("Weekend")
  case _ => println("Weekday")
}

Scala | Decision Making

1. if Statement

2. if-else Statement

3. if-else-if Ladder