For Loop in Dart

29 March, 2023

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For Loop

In the Dart programming language, the for loop allows a programmer to repeat a block of code a specific number of times. It is a useful control flow statement for executing a block of code repeatedly until a certain condition is met.

Syntax

The syntax for a for loop in Dart is as follows:

for (initialization; condition; increment) {
  // code to be executed
}

The initialization statement is executed once before the loop starts. The condition is checked before each iteration of the loop, and the loop will continue as long as the condition is true. The increment statement is executed after each iteration of the loop.

Example

Here is an example of a for loop that counts from 1 to 10:

for (int i = 1; i <= 10; i++) {
  print(i);
}

Here is an example of a for loop that counts down from 100 to 1:

for (int i = 100; I >= 1; i--) {
  print(i);
}

This code would output the numbers 1 through 10 to the console.

`for` loop with `List`

The for loop can also be used to iterate over the elements in a List. Here is an example of a for loop that prints out the elements in a List:

List<String> fruits = ["apple", "banana", "orange"];

for (int i = 0; i < fruits.length; i++) {
  print(fruits[i]);
}

This code would output "apple", "banana", and "orange" to the console.

`for` loop with `Map`

The for loop can also be used to iterate over the key-value pairs in a Map. Here is an example of a for loop that prints out the key-value pairs in a Map:

Map<String, int> prices = {"apple": 0.99, "banana": 0.79, "orange": 0.59};

for (String key in prices.keys) {
  print("The price of a $key is ${prices[key]}");
}

This code would output "The price of a apple is 0.99", "The price of a banana is 0.79", and "The price of a orange is 0.59" to the console.

for in loop

In Dart, the for-in-loop is used to iterate over the elements of an iterable object, such as a list or a set. Here is an example of how to use a for-in-loop

void main() {
  List<String> names = ['Alice', 'Bob', 'Charlie', 'Dave'];

  for (String name in names) {
    print(name);
  }
}

In this example, we define a List ofStrings called names. We then use a for-in loop to iterate over the elements of the list. The loop variable name is declared as aString, and it takes on the value of each element in names in turn.

The loop body simply prints the value of name to the console using the print() function. This loop will print the names 'Alice', 'Bob', 'Charlie', and 'Dave' to the console, one per line.

You can use the for-in loop with any iterable object in Dart, such as lists, sets, maps, and strings. Note that when using a for-in loop with a Map, the loop variable takes on the keys of the map by default. If you want to iterate over the values or key-value pairs of the map, you can use the values or entries property, respectively.

Conclusion

The for loop is a useful control flow statement in the Dart programming language. It allows a programmer to repeat a block of code a specific number of times, or iterate over the elements in a List or Map. It is an efficient way to perform a task multiple times in a program.