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using yield return with Enumerable in C#

Dilshodbek Hamidov answered on December 22, 2022 Popularity 3/10 Helpfulness 1/10

answer using yield return with Enumerable in C#

using yield return with Enumerable in C#

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// Here's a variable to track execution of code in an iterator
int lastYielded = -1;

// Here's an iterator for us to play with
IEnumerable<int> GetOneToTen() {
  for (var num = 1; num <= 10; num++) {
    lastYielded = num;
    yield return num;
  }
}

void Main() {
  var numbers = GetOneToTen();
  lastYielded.Dump(); // Output: -1

  // This gives us an 'instance' of the iteration
  var enumerator = numbers.GetEnumerator();

  // This executes the iterator until the first yield return is reached
  enumerator.MoveNext();

  // This gives us the current (most recently yielded) value of the iterator
  enumerator.Current.Dump(); // Output: 1
  lastYielded.Dump(); // Output: 1

  // This will iterate from 1 to 4, then stop
  foreach (var num in numbers) {
    if (num >= 4) {
      break;
    }
  }

  lastYielded.Dump(); // Output: 4

  // This will not execute any code in the iterator.
  //  LINQ methods are lazily evaluated as well
  var numbersTimesTwo = numbers.Select(num => num * 2);
  lastYielded.Dump(); // Output: 4

  // This will force the entire iterator to run, yielding all values
  var arr = numbers.ToArray();
  lastYielded.Dump(); // Output: 10
}

Popularity 3/10 Helpfulness 1/10 Language csharp

Source: stackoverflow.blog

Tags: c# enumerable using yield-return

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Contributed on Dec 22 2022

Dilshodbek Hamidov

0 Answers Avg Quality 2/10

using yield return with Enumerable in C#

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