Dart - Loop Control Statements (Break and Continue)

Dart supports two types of loop control statements:

• Break Statement
• Continue Statement

Break Statement

This statement is used to break the flow of control of the loop i.e. if it is used within a loop then it will terminate the loop whenever encountered. It will bring the flow of control out of the nearest loop.

Syntax:

break;

- Using break inside while loop

Example :

void main()
{
    int count = 1;

    while (count <= 10) {
        print("Geek, you are inside loop $count");
        count++;

        if (count == 4) {
            break;
        }
    }
    print("Geek, you are out of while loop");
}

Output:

Geek, you are inside loop 1
Geek, you are inside loop 2
Geek, you are inside loop 3
Geek, you are out of while loop

Explanation of the above Program:

Initially count value is 1, as it goes inside loop the condition is checked, 1 <= 10 and as it is true the statement is printed variable is increased and then condition is checked, 2 == 4, which is false then the loop is followed again till the condition 4 == 4 is encountered and the flow comes out of the loop and then last print statement is executed.

- Using break inside do..while loop

Example :

void main()
{
    int count = 1;

    do {
        print("Geek, you are inside loop $count");
        count++;

        if (count == 5) {
            break;
        }
    } while (count <= 10);
    
    print("Geek, you are out of do..while loop");
}

Output :

Geek, you are inside loop 1
Geek, you are inside loop 2
Geek, you are inside loop 3
Geek, you are inside loop 4
Geek, you are out of do..while loop

- Using break inside for loop

Example :

void main()
{
    for (int i = 1; i <= 10; ++i) {
        if (i == 2)
            break;

        print("Geek, you are inside loop $i");
    }

    print("Geek, you are out of loop");
}

Output:

Geek, you are inside loop 1
Geek, you are out of loop

Continue Statement

While the break is used to end the flow of control, continue on the other hand is used to continue the flow of control. When a continue statement is encountered in a loop it doesn't terminate the loop but rather jump the flow to next iteration.

Syntax:

continue;

- Using continue inside a while loop

Example :

void main()
{
    int count = 0;

    while (count <= 10) {
        count++;

        if (count == 4) {
            print("Number 4 is skipped");
            continue;
        }

        print("Geek, you are inside loop $count");
    }

    print("Geek, you are out of while loop");
}

Output:

Geek, you are inside loop 1
Geek, you are inside loop 2
Geek, you are inside loop 3
Number 4 is skipped
Geek, you are inside loop 5
Geek, you are inside loop 6
Geek, you are inside loop 7
Geek, you are inside loop 8
Geek, you are inside loop 9
Geek, you are inside loop 10
Geek, you are inside loop 11
Geek, you are out of while loop

Explanation of the above Program:

Here control flow of the loop will go smooth but when count value becomes 4 the if condition becomes true and the below statement is skipped because of continue and next iteration skipping number 4.

- Using continue inside do..while loop

Example :

void main()
{
    int count = 0;

    do {
        count++;

        if (count == 4) {
            print("Number 4 is skipped");
            continue;
        }

        print("Geek, you are inside loop $count");
    } while (count <= 10);
    
    print("Geek, you are out of while loop");
}

Output:

Geek, you are inside loop 1
Geek, you are inside loop 2
Geek, you are inside loop 3
Number 4 is skipped
Geek, you are inside loop 5
Geek, you are inside loop 6
Geek, you are inside loop 7
Geek, you are inside loop 8
Geek, you are inside loop 9
Geek, you are inside loop 10
Geek, you are inside loop 11
Geek, you are out of while loop

- Using continue inside the for loop

Example :

void main()
{
    for (int i = 1; i <= 10; ++i) {

        if (i == 2) {
            print("Geek, you are inside loop $i");
            continue;
        }
    }

    print("Geek, you are out of loop");
}

Output:

Geek, you are inside loop 2
Geek, you are out of loop

Conclusion

Loop control statements in Dart are essential for managing the execution of loops based on specific conditions. Here’s a clearer breakdown:

break Statement

• The break statement immediately exits the nearest loop when it is encountered.
• It is useful for stopping execution once a certain condition is met.
• This statement works with for, while, and do...while loops.

continue Statement

• The continue statement skips the current iteration of the loop and proceeds to the next one.
• It is helpful when you want to ignore specific conditions but continue with the looping process.
• This statement also works with for, while, and do...while loops.

By effectively utilizing break and continue, you can optimize loops to prevent unnecessary iterations and control the flow better.