Help with this Lamda Expression

Question

Hi I am learning Lamda Expressions and I find it hard to understand the below expression. Can some one please explain. I took it from msdn. int[] numbers = { 5 4 1 3 9 8 6 7 2 0 }; var firstSmallNumbers = numbers.TakeWhile((n index) => n >= index); As per my understanding the above expression is trying to get all the numbers whose value >= its position. So the output should be(values): 543987 and index(0134567) But the original output is 54 Appreicate your help. Thanks. Aravind

Manikavelu Velayutham · Answer

Absolutely Not. You have misunderstood the functionality. From the word itself you should understand how it works. TakeWhile --> Take the words Until the condition satisfies. From your example its iterating starting from 5. For 5 --> Condition is true For 4 --> Condition is true For 1 --> Condition Fails. So its stop printing after 4. It wont proceed further. Thats why the output 5 4 Hope you understood. Let me know if you still need clarification. Another example for you. string [] fruits = { apple  banana  mango  orange  passionfruit  grape }; IEnumerable string > query = fruits.TakeWhile(fruit => String.Compare( orange  fruit true ) != 0); foreach ( string fruit in query) { Console.WriteLine(fruit); } /* This code produces the following output: apple banana mango */ Here the above program prints the fruit name until it matches the fruit name orange. Its a cool functionality and its more useful in iterations. You can use it in a situation like you can do the looping until the condition satisfies. Its just a single line of code. Thats the Functional Programming.

Manikavelu Velayutham · Answer

Little more clear explanation. If you change the inputs like int [] numbers = { 15 14 11 13 19 18 16 17 12 8 }; output will be 15 14 11 13 19 18 16 17 12 Here why the 8 is not printed means 8 >= 9 whereas 8 is the element 9 is the index of 8. Condition fails here. so it wont print 8

aravind Gosh · Answer

Thank You very much Manikvelu. Its really is a good explanation.