For Loop in Dart

Syntax of For Loop in Dart

The syntax of For loop in Dart is as follows:

• Initialization: This step initializes a variable before the loop starts. It typically sets the starting point for the iteration.
• Condition: The loop's execution continues as long as this condition holds true. If the condition evaluates to false, the loop terminates.
• Increment: After each iteration, this step updates the loop control variable. It's responsible for progressing towards the termination condition.

The code within the curly braces {} represents the block of code to be executed during each iteration.

Examples

1. Looping with Ranges and Step Values: This example demonstrates how to loop over a range of numbers using a "for loop" with a step value. It starts at 1 and iterates up to 10, incrementing by 2 in each step. This way, it only considers odd numbers within the specified range.

Output:

2. Looping through Strings: In this scenario, the "for loop" iterates over each character in the string "Hello, Dart!" using the loop control variable i. The loop runs until i reaches the length of the string. Each character is printed on a separate line.

   Output:

3. Looping through List: Explanation: Here, the "for loop" iterates through a list of integers [2, 4, 6, 8, 10]. In each iteration, the loop control variable number takes on the value of the current element in the list and is printed.

   Output:

4. Iterating Over Maps and Iterables: This example first iterates over a map ages containing names and ages. The loop control variable entry represents each key-value pair in the map, which is printed out. The second part demonstrates iterating over an iterable fruits of strings. The loop control variable fruit takes on each value from the iterable and prints it.

   Output:

5. Iterating Over Enumerations: In this example, the "for loop" iterates over all the values in the Weekday enumeration. The loop control variable day represents each value in the enumeration and is printed.

   Output:

Nested For Loop in Dart

A nested for loop in Dart is a loop structure that contains another loop inside it. This creates a hierarchical looping structure, where the inner loop is fully executed for each iteration of the outer loop. Nested for loops are useful for working with two-dimensional data structures, performing tasks involving multiple levels of iteration, or handling patterns that involve combinations of values. However, using nested loops can increase code complexity and potentially impact performance, so they should be used judiciously.

Syntax:

Example: Printing a Pattern

In this example, the outer loop runs from i = 1 to i = 5. For each value of i, the inner loop runs from j = 1 to j = i, printing an asterisk '*' in each iteration of the inner loop. This creates a pattern of asterisks where the number of asterisks increases with each row. The output would be:

Remember that in nested loops, the inner loop's full execution occurs for each iteration of the outer loop. So, in the example above, the inner loop will run once for i = 1, twice for i = 2, and so on.

Infinite For Loop in Dart

An Infinite For Loop is a programming construct where a loop runs indefinitely, repeatedly executing a block of code without any predefined stopping condition. This type of loop is often used when you want to create a continuous process or keep a certain section of code running until an external action is taken to terminate it.

Syntax:

Example:

In this example, the loop runs indefinitely, repeatedly printing the given message. To control an infinite loop, you usually use an exit condition that you can set within the loop to break out of it.

Loop Control Statements

In Dart programming, loop control statements are used to control the flow of execution within loops. They allow you to modify the behavior of loops by altering when and how the loop iterates or terminates. Dart provides three main types of loop control statements: break, continue, and return.

Break Statement:

The break statement is used to immediately exit the innermost loop in which it appears. It terminates the loop prematurely and continues the execution of the program after the loop. Here's an example:

Output:

In this example, the loop will run from i = 1 to i = 3, and then the break statement will be encountered, causing the loop to terminate.

Continue Statement:

The continue statement is used to skip the current iteration of the loop and move on to the next iteration. It does not terminate the loop but simply skips the remaining code within the loop for the current iteration. Here's an example:

Output:

In this example, when i is equal to 3, the continue statement is encountered, and the loop skips the rest of the code inside the loop for that iteration, moving on to the next iteration.

Return Statement (within a function):

While not specifically a loop control statement, the return statement can also be used to exit a loop early if it appears within a loop that is contained within a function. When the return statement is executed within the loop, it not only exits the loop but also exits the entire function in which the loop resides.

Output:

In this example, when the loop within the containsValue function encounters the value 3, the return true statement is executed, immediately exiting both the loop and the function.

These loop control statements provide you with the flexibility to manage the flow of your program within loops, allowing you to control when and how iterations are processed or terminated.