# 
#  The `putIfAbsent()` method

In Dart, the **`putIfAbsent()` method** checks the value of `key` or creates one if it doesn't exist.

## Syntax

---
```
V putIfAbsent (K key, V ifAbsent())
```
---

## Parameters and return value 

If there is a value associated with `key`, it is returned. Otherwise, it uses `ifAbsent()` to get a new value, associates `key` with it, and returns the new value.

##
## Code

void main() {
  
  Map<String, int> age = {'Eva': 16};
  
  print('The orignal map: ${age}');

  for (var key in ['Tobby', 'Eddie', 'Maria']) {
    age.putIfAbsent(key, () => key.length * 2);
  }
  print('The new map:${age}');
}

# 
## Explanation

- In the code above, we create a map named `age`. 

- Next, we use the `for` loop to iterate over the iterable and pass the `putIfAbsent` method, which returns the value associated to `key`, if there is one.  

- Otherwise, it calls `ifAbsent` to get a new value, associates `key` with it, and returns the new value.

What is map.putIfAbsent() in Dart?

Checks the value of a key or creates one if it doesn’t exist, returning the value.

What is map.putIfAbsent() in Dart?

The putIfAbsent() method

Syntax

Parameters and return value

Code

Explanation

The `putIfAbsent()` method