Stateful Iterators for Deferred Complex Logic

Snippet

Stateful Iterators for Deferred Complex Logic

The 'yield' keyword transforms a method into a state machine. This allows for complex control flow and sequences to be generated lazily, preventing unnecessary memory allocations for large datasets.

snippet.cs

csharp

public static IEnumerable<long> FibonacciSequence(int limit) {
    long prev = 0, current = 1;
    for (int i = 0; i < limit; i++) {
        yield return prev;
        long next = prev + current;
        prev = current;
        current = next;
    }
}
 
// Usage: var data = FibonacciSequence(10).Where(n => n % 2 == 0);

Breakdown

yield return prev;

Suspends execution and returns a value to the caller, preserving the local state for the next iteration.

IEnumerable<long>

Defines the return type as a lazy sequence that only executes when iterated over (deferred execution).

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Stateful Iterators for Deferred Complex Logic

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