loop in dart

Loops in Dart

Loops are fundamental for performing repetitive tasks in programming. Dart provides several types of loops to handle different scenarios. Below is a comprehensive guide on each type:

For Loop in Dart

About

The for loop is used to repeat a block of code a specified number of times. It is commonly used when the number of iterations is known beforehand.

How to Use

A for loop consists of three main parts:

  1. Initialization: Sets the starting value.
  2. Condition: Evaluates if the loop should continue.
  3. Increment/Decrement: Updates the loop variable.

How It Works

  • Initializes the loop variable.
  • Checks the condition; if true, executes the block of code.
  • Updates the loop variable.
  • Repeats until the condition is false.

Example

for (int i = 0; i < 5; i++) {
  print('Iteration $i');
}

In this example, the loop prints “Iteration 0” to “Iteration 4”, running the code block 5 times.

Range-based For Loop

About A range-based for loop is used to iterate over a range of numbers or items in a collection.

How to Use

Utilizes a collection or range to iterate through its elements.

How It Works

Iterates over each item in the range or collection. Executes the code block for each item.

  • Example
for (int num in [1, 2, 3, 4, 5]) {
  print(num);
}

This example prints each number in the list [1, 2, 3, 4, 5].

For-Each Loop in Dart

  • About

The for-each loop simplifies iterating over collections such as lists or sets.

How to Use

Uses the for-in syntax to iterate over elements in a collection. How It Works Iterates over each element in the collection. Executes the block of code for each element.

  • Example
List<String> names = ['Alice', 'Bob', 'Charlie'];
for (String name in names) {
  print(name);
}

This example prints each name in the names list.

While Loop in Dart

  • About The while loop repeatedly executes a block of code as long as its condition evaluates to true.

How to Use

Requires a condition to be checked before each iteration.

How It Works

Checks the condition before each loop iteration. Executes the block of code if the condition is true. Repeats until the condition is false.

  • Example
int count = 0;
while (count < 5) {
  print('Count is $count');
  count++;
}

This loop prints “Count is 0” to “Count is 4”, running until count is no longer less than 5.

  • About

The do-while loop executes a block of code once before checking the condition and then continues executing as long as the condition is true.

How to Use

  • Ensures that the code block executes at least once.

How It Works

  • Executes the code block once.
  • Checks the condition after the code block executes.
  • Continues looping as long as the condition remains true.

Example

int count = 0;
do {
  print('Count is $count');
  count++;
} while (count < 5);

This loop prints “Count is 0” to “Count is 4”, similar to the while loop, but guarantees at least one execution of the code block.