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.