Control flow

Control flow statements determine the order in which code is executed.

if expression

Executes a block of code when a condition is true

if (condition) {
  //Block of code to be executed if the condition is true
} else {
  //Block of code to be executed if the condition is false
}

Example

val x = 1
val y = 5
if (x >= y) {
  println("x is greater than or equal to y")
} else {
  println("x is smaller than y")
}
//>> x is smaller than y

while loop

Executes a block of code while a condition is true

while (condition) {
  //Block of code to be executed if the condition is true
}

Example

var x = 1
val y = 5
while (x < y) {
  println(x)
  x += 1
}
//>> 1
//>> 2
//>> 3
//>> 4

for loop

Use a for loop when the number of iterations is known.

The default variableName is set to val and is a temporary variable.

for (variableName in start..end) {
  //Block of code to be executed if the condition is true
}

Example

for (i in 0..2) {
  println(i)
}
//variable i won't exist outside the for statement 
//>> 0
//>> 1
//>> 2

You can also use an existing variable instead of declaring a new one

for (tempVariable in start..end) {
  //Block of code to be executed if the condition is true
}

Example

var i = 5
for (i in 0..2) {
  println(i)
}
println(i) 
//>> 0
//>> 1
//>> 2
//>> 3

If you want loop until end, you can use ..<

for (variableName in start..<end) {
  //Block of code to be executed if the condition is true
}
for (variableName in start..<end) {
  //Block of code to be executed if the condition is true
}

Example

for (i in 0..<2) {
  println(i)
}
//>> 0
//>> 1

If you want loop until end, you can use ..<

break and continue

Sometimes, you want to skip or break a loop, you can use continue or break

Example continue

for (i in 0..2) {
  if (i == 1) {
    continue //Skip
  }
  println(i)
}
//>> 0
//>> 2

Example break

for (i in 0..2) {
  if (i == 1) {
    break //Break
  }
  println(i)
}
//>> 0

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