Dart Loops - 5 types of Loops You Must Know

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Dart Loops Tutorial and Examples.

Dart supports various types of loops. Let's explore them.

1. Standard For Loops

Here's an example:

main() {
  // A standard for loop
  for (var i = 0; i < 10; i++) {
    print(i);
  }
}

And we get:

0
1
2
3
4
5
6
7
8
9

2. For - in Loops

If you are working with a class that implements Iterable, then you can use the for-in loops.

Here's an example:

main() {
  var spaceprobes = ["Casini","James Web","Spitzer","Juno","WMAP", "Kepler","Swift"];
  for (var probe in spaceprobes) {
    print(probe);
  }

}

And we get:

Casini
James Web
Spitzer
Juno
WMAP
Kepler
Swift

3. forEach

Here's an example of forEach loop:

main() {
  var planets = ["Earth","Mercury","Saturn","Venus","Jupiter","Neptune", "Uranus","Mars"];
  planets.forEach((planet) => print(planet)); // invoke each callback

}

And we get:

Earth
Mercury
Saturn
Venus
Jupiter
Neptune
Uranus
Mars

This is a very commonly used looping construct. For example consider [a real world scenario where you are fetching data from database(/flutter/sqflite)]:

    Future fetchEveryone() async {
      List results = await _db.query("people", columns: Person.columns);
      List people = new List();
      results.forEach((map) {
        people.add(Person.fromMap(map));
     });
    return people;
    }

4. While Loops

While conditions in Dart, like in many other programming languages, are evaluated before the loop.

Here's a while loop example:

main() {
  var count = 1;

  while(count <= 10) {
    print("I love You Dart $count");
    count++;
  }

}

Result:

I love You Dart 1
I love You Dart 2
I love You Dart 3
I love You Dart 4
I love You Dart 5
I love You Dart 6
I love You Dart 7
I love You Dart 8
I love You Dart 9
I love You Dart 10

5. Do- While Loops

The do-while conditions are evaluated after the loop:

Here's an example:

main() {
  var count = 1;

  do {
    print("I love You Dart $count");
    count++;
  } while (count <= 10);
}

Result:

I love You Dart 1
I love You Dart 2
I love You Dart 3
I love You Dart 4
I love You Dart 5
I love You Dart 6
I love You Dart 7
I love You Dart 8
I love You Dart 9
I love You Dart 10

How do You Feel after reading this?

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About Me.

After completing his Software Engineering bachelors program, Oclemy(Clement Ochieng) these days is a man of two lives. At day he works for a startup in Nairobi, Kenya. At night he works tirelessly on building ProgrammingWizards TV, a tv channel for student coders and this website to help share the source code. In between he practices Meditation and Self actualization to help him keep balance. He also likes going for long solo walks to connect more with nature.




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