Kotlin Unlabelled break

When we are working with loops and want to stop the execution of loop immediately if a certain condition is satisfied, in this case, we can use either break or return expression to exit from the loop. 
In this article, we will discuss learn how to use break expression to exit a loop. When break expression encounters in a program it terminates to nearest enclosing loop.

There are two types of break expressions in Kotlin: 
We are going to learn how to use unlabelled break expression in while, do-while, and for loops. 

Use of an unlabelled break in a while loop

Unlabelled break is to used to exit the loop when it satisfies a specific condition without checking the test expression. Then, transfers the control to the following statement of while block. 

Syntax of break in a while loop

while(test expression) {
       // code to run
            if(break condition) {
              break
            }
      // another code to run
}

Flowchart

Kotlin program to find the sum of integers from 1 to 10.

fun main(args: Array<String>) {

    var sum = 0
    var i = 1
    
    while(i <= Int.MAX_VALUE) {
    
        sum += i
        i++
        if(i == 11) {
            break
        }
    }
    
    print("The sum of integers from 1 to 10: $sum")
}

Output:

The sum of integers from 1 to 10: 55

In the above program, we calculate the sum of integers from 1 to 10 with the help of while loop and break expression. Take a variable sum and initialize it with 0. Another variable i to iterate through the loop and initialize it with 1. 
Now, the iterator continues from (i = 1) and executes the sum statement. When the iterator value i becomes 11, then it executes the break expression and exits the loop without checking the test expression (i <= Int.MAX_VALUE). Then, control passes to the following statement print() of the while block, and it prints the sum of integers = 55
 

Use of an unlabelled break in a do-while loop

In a do-while loop, we can also use the break expression to exit the loop without checking the test expression.

Syntax for break in do-while loop

do {
   //code to run
     if(break condition) {
           break
     }
while(test expression)

Flowchart
 

Kotlin program to print the elements of an array 

fun main(args: Array<String>) {

    var names = arrayOf("Earth","Mars","Venus","Jupiter","Saturn","Uranus")
    var i = 0

    do{
    
        println("The name of $i th planet: "+names[i])
        if(names[i]=="Jupiter") {
            break
        }
        i++
    }while(i<=names.size)
}

Output: 

The name of 0 th planet: Earth
The name of 1 th planet: Mars
The name of 2 th planet: Venus
The name of 3 th planet: Jupiter

In the above program, we traverse the array to print names of planets. First of all, initialize an array names with planet names and i is the iterator for test expression. We calculate the size of an array using names.size. 
do block first print the element of the array, and every time the value of the array at any index is compared with "Jupiter". If it does match, then increment the iterator and execute again. If the condition is true, then execute the break expression and exit the do-while loop without checking for the test expression.
 

Use of an unlabelled break in a for loop

We can use a break expression while traversing the for loop within an array or string. 

Syntax of break in a for loop

for(iteration through iterator) {
               // code to run
      if(break condition){
          break
      }
}

Flowchart
 

Kotlin program to print a string upto a particular character 
In the program below, we traverse the string to break at a particular position by comparing the char value. First of all, initialize an array name with the value "GeeksforGeeks". Then a for loop to traverse using an iterator i. It prints the char value and compares it at each position with char 's'. If matches, then exit the loop and transfer control to the following statement. 

fun main(args: Array<String>) {

    var name = "GeeksforGeeks"
    for (i in name){
     print("$i")
          if(i == 's') {
            break
          }
    }
}

Output:

Geeks