Just trying to see if C# select has the same capabilities like javascript map or not (doing some computations and then returning at the end).
For example:
const numberList = [1,2,3,4,5];
const newNumberList = numberList.map(number => {
const modifiedNumber = number * 2;
return modifiedNumber;
})
Yes, in this example, I can just do number => number * 2. But I am wondering for more complex scenarios where I need to do some function calls to figure out some values and then make use of them and return a list at the end.
You've got three options, one of which you've already pointed out.
One - single statement lambda
int[] numbers = { 1, 2, 3, 4, 5 };
int[] newNumbers = numbers.Select(x => x * 2).ToArray();
Two - multi-statement lambda
int[] newNumbers = numbers
.Select(x => {
var newVal = x * 2;
return newVal;
})
.ToArray();
Three - use an actual method (rather than anonymous method)
private static int MultByTwo(int val)
{
return val * 2;
}
// ...
int[] newNumbers = numbers.Select(MultByTwo).ToArray();
Note, you don't write MultByTwo(), it's just the name of the method.
Yes, Select is the equivalent of map. Indeed, LINQ is a functional interface over IEnumerable<T> just like the JS implementation on arrays. The signature is:
IEnumerable<T> => (T => R) => IEnumerable<R>
As long as you adhere to the Select contract you can write more complex code that calls functions that call other functions and so on.