Finished

Numbers/NumberString/DigitEnumerator.cs

@@ -8,9 +8,8 @@ namespace Numbers.NumberString;
 /// <inheritdoc cref="IEnumerator{T}"/>
 public sealed class DigitEnumerator : IEnumerator<int>
 {
-    // TODO
-    // private readonly string _text;
-    // private int _index;
+    private readonly string _text;
+    private int _index;
 
     /// <summary>
     ///     Creates a new instance of <see cref="DigitEnumerator"/> based on the given text.
@@ -19,35 +18,42 @@ public sealed class DigitEnumerator : IEnumerator<int>
     /// <param name="text">The text to iterate over (containing both letters and digits)</param>
     public DigitEnumerator(string text)
     {
-        // TODO
+        _text = text;
+        _index = -1;
     }
 
     public bool MoveNext()
     {
-        // TODO
+        while (++_index < _text.Length)
+        {
+            if (char.IsDigit(_text[_index]))
+            {
+                return true;
+            }
+        }
         return false;
     }
 
     public void Reset()
     {
-        // TODO
+        _index = -1;
     }
 
     public int Current
     {
         get
         {
-            // TODO
-            return -1;
-
-            //static int GetDigit(char c) => c - '0';
+            if (_index < 0 || _index >= _text.Length || !char.IsDigit(_text[_index]))
+            {
+                return -1;
+            }
+            
+            return GetDigit(_text[_index]);
+            static int GetDigit(char c) => c - '0';
         }
     }
 
-    object IEnumerator.Current => null!; // TODO
+    object IEnumerator.Current => Current;
 
-    public void Dispose()
-    {
-        // TODO?
-    }
+    public void Dispose() { }
 }