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Lambda Expressions Extension Method 4 – TakeWhile()

Posted by Paul on May 14, 2011


The method TakeWhile() is a tricky method. It will take a condition as parameter and it will return the elements until the condition is true and exists the iteration.

It is not similar to Where() condition. Let me take an example. We have 1, 2, 3, 4, 5, 6 in the list and given a condition TakeWhile(i => I != 2) it will return just 1. The method works like below:

It will go through element 1 and as it satisfies the condition it will be yield returned.

On the second element 2 the condition is false and it will exits.

There is no processing for element 3.

Arguments: Condition

Return Value: List of Items


In the following example we are using a list of integers and the Take() method to select the top n numbers from the list.

private IList<int> _list = new List<int>();

public InitializeList()


// Set data








private void TakeWhileButton_Click(object sender, EventArgs e)


/// TakeWhile method to get a sublist based on condition

var result = _list.TakeWhile(i => i != 2);

foreach (int i in result)



Extension Method Snapshot

You can find the snapshot of the TakeWhile() method usage as provided by Visual Studio



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