feat(*): Add SubstringBetween method

Creek.HelpfulExtensions/StringExtension.cs

@@ -4,5 +4,27 @@ namespace Creek.HelpfulExtensions
 {
     public static class StringExtension
     {
+        /// <summary>
+        /// Returns a substring from the first occurrence of the start string to the end string.
+        /// </summary>
+        /// <param name="str">The string to find a substring from.</param>
+        /// <param name="startString">The string to begin the substring with.</param>
+        /// <param name="endString">The string that should occur immediately after the substring.</param>
+        /// <param name="isLastEndStringOccurence">Allows selecting whether to use the first occurrence of the endString (default behaviour) or the last.</param>
+        /// <returns>Returns the substring.</returns>
+        public static string SubstringBetween(this string str, string startString, string endString, bool isLastEndStringOccurrence = false)
+        {
+            // Find the start index of the startString
+            int startIndex = str.IndexOf(startString);
+
+            // Find the end index of the endString
+            int endIndex = isLastEndStringOccurrence ? str.LastIndexOf(endString) : str.IndexOf(endString);
+
+            // Find the length of the string we want
+            int length = endIndex - startIndex;
+
+            // Substring(int startIndex, int length)
+            return str.Substring(startIndex, length);
+        }
     }
 }