I'm trying to think of clever, clear, and simple ways to write code that describes the sequence of integers in a given range.
Here's an example:
IEnumerable<int> EnumerateIntegerRange(int from, int to)
{
for (int i = from; i <= to; i++)
{
yield return i;
}
}
This is already in the framework: Enumerable.Range .
For other types, you might be interested in the range classes in my MiscUtil library.
Alternately, a fluent interface from extension methods:
public static IEnumerable<int> To(this int start, int end)
{
return start.To(end, i => i + 1);
}
public static IEnumerable<int> To(this int start, int end, Func<int, int> next)
{
int current = start;
while (current < end)
{
yield return current;
current = next(current);
}
}
used like:
1.To(100)
Here's an idea that lets a range class work with both things that are discrete and those which are not:
class Range<T> where T: IComparable<T>
{
public T From { get; set; }
public T To { get; set; }
public Range(T from, T to) { this.From = from; this.To = to; }
public IEnumerable<T> Enumerate(Func<T, T> next)
{
for (T t = this.From; t.CompareTo(this.To) < 0; t = next(t))
{
yield return t;
}
}
static void Example()
{
new Range<int> (0, 100).Enumerate(i => i+1)
}
}
And if you think that supplying the enumerator each time is annoying, here's a derived class:
class EnumerableRange<T> : Range<T>, IEnumerable<T>
where T : IComparable<T>
{
readonly Func<T, T> _next;
public EnumerableRange(T from, T to, Func<T, T> next)
: base(from, to)
{
this._next = next;
}
public IEnumerator<T> GetEnumerator()
{
return Enumerate(this._next).GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return this.GetEnumerator();
}
}
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