initial commit

2020-06-14 21:48:39 +02:00
parent 924d32929b
commit 3c3b9dd7ed
15 changed files with 520 additions and 0 deletions
--- a/TrailingNumberFromString.cs
+++ b/TrailingNumberFromString.cs
@@ -0,0 +1,118 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Text.RegularExpressions;
+using BenchmarkDotNet.Attributes;
+
+namespace Benchmark
+{
+    [MemoryDiagnoser]
+    public class TrailingNumberFromString
+    {
+        private readonly Regex _regex = new Regex(@"^\d$", RegexOptions.Compiled);
+
+        [Benchmark]
+        public int? GetTrailingNumberFromString1()
+        {
+            const string foo = "Test1234";
+            string sValue = null;
+
+            for (var i = foo.Length - 1; i >= 0; i--)
+            {
+                var regex = new Regex(@"^\d$");
+
+                if (regex.IsMatch(foo[i].ToString()))
+                    sValue = foo[i] + sValue;
+                else
+                    break;
+            }
+
+            if (sValue != null)
+                return Convert.ToInt32(sValue);
+
+            return null;
+        }
+
+        [Benchmark]
+        public int? GetTrailingNumberFromString2()
+        {
+            const string foo = "Test1234";
+            string sValue = null;
+
+            for (var i = foo.Length - 1; i >= 0; i--)
+            {
+                if (_regex.IsMatch(foo[i].ToString()))
+                    sValue = foo[i] + sValue;
+                else
+                    break;
+            }
+            if (sValue != null)
+                return Convert.ToInt32(sValue);
+
+            return null;
+        }
+
+        [Benchmark]
+        public int? GetTrailingNumberFromString3()
+        {
+            const string foo = "Test1234";
+            var result = 0;
+
+            for (var i = foo.Length - 1; i >= 0; i--)
+            {
+                if (foo[i] >= 48 && foo[i] <= 58)
+                {
+                    var value = foo[i] - 48;
+                    result += value * (int) Math.Pow(10, foo.Length - i - 1);
+                    continue;
+                }
+
+                break;
+            }
+
+            return result;
+        }
+
+        [Benchmark]
+        public int? GetTrailingNumberFromString4()
+        {
+            const string foo = "Test1234";
+            var result = 0;
+            
+            for (var i = foo.Length - 1; i >= 0; i--)
+            {
+                if (foo[i] >= 48 && foo[i] <= 58)
+                {
+                    var value = foo[i] - 48;
+                    result += value * IntegerPow(10, foo.Length - i - 1);
+                    continue;
+                }
+
+                break;
+            }
+
+            return result;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static int IntegerPow(int x, int y)
+        {
+            if (y == 0) return 1;
+            var result = x;
+            for (var i = 1; i < y; i++)
+            {
+                result *= x;
+            }
+
+            return result;
+        }
+        
+        [Benchmark]
+        public int? GetTrailingNumberFromString5()
+        {
+            const string foo = "Test1234";
+            var regex = new Regex(@"\d+$");
+            var match = regex.Match(foo);
+            return match.Success && int.TryParse(match.Value, out var result) ? result : default(int?);
+        }
+    }
+}