Counting char occurrences: retarget net10.0, fix IndexOf undercount, Regex.Count

strings-csharp/CountingCharOccurences/CountingCharOccurences/CountChars.cs

@@ -1,7 +1,6 @@
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Order;
 using System.Text.RegularExpressions;
-using CommunityToolkit.HighPerformance;
 
 namespace CountingCharOccurences
 {
@@ -59,10 +58,7 @@ public int CountCharsUsingIndex(string source, char toFind)
             int n = 0;
 
             while ((n = source.IndexOf(toFind, n) + 1) != 0)
-            {
-                n++;
                 count++;
-            }
 
             return count;
         }
@@ -130,7 +126,7 @@ public int CountCharsUsingReplace(string source, char toFind)
         [ArgumentsSource(nameof(GenerateStringWithCharArgs))]
         public int CountCharsUsingRegex(string source, char toFind)
         {
-            return new Regex(Regex.Escape(toFind.ToString())).Matches(source).Count;
+            return Regex.Count(source, Regex.Escape(toFind.ToString()));
         }
 
         [Benchmark]

strings-csharp/CountingCharOccurences/CountingCharOccurences/CountSubstringsAndFrequencies.cs

@@ -0,0 +1,35 @@
+namespace CountingCharOccurences
+{
+    public class CountSubstringsAndFrequencies
+    {
+        public int CountSubstringNonOverlapping(string source, string toFind)
+        {
+            return source.AsSpan().Count(toFind);
+        }
+
+        public int CountSubstringOverlapping(string source, string toFind)
+        {
+            var count = 0;
+
+            for (var n = 0; (n = source.IndexOf(toFind, n, StringComparison.Ordinal)) != -1; n++)
+                count++;
+
+            return count;
+        }
+
+        public Dictionary<char, int> CountEveryCharUsingLinq(string source)
+        {
+            return source.GroupBy(c => c).ToDictionary(g => g.Key, g => g.Count());
+        }
+
+        public Dictionary<char, int> CountEveryCharUsingLoop(string source)
+        {
+            var counted = new Dictionary<char, int>();
+
+            foreach (var c in source)
+                counted[c] = counted.GetValueOrDefault(c) + 1;
+
+            return counted;
+        }
+    }
+}

strings-csharp/CountingCharOccurences/CountingCharOccurences/CountingCharOccurences.csproj

@@ -2,17 +2,13 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="BenchmarkDotNet" Version="0.13.2" />
-    <PackageReference Include="CommunityToolkit.HighPerformance" Version="8.0.0" />
+    <PackageReference Include="BenchmarkDotNet" Version="0.15.8" />
   </ItemGroup>
 
-  <ItemGroup>
-    <None Remove="CommunityToolkit.HighPerformance" />
-  </ItemGroup>
 </Project>

strings-csharp/CountingCharOccurences/CountingCharOccurences/Program.cs

@@ -1,12 +1,4 @@
 using BenchmarkDotNet.Running;
+using CountingCharOccurences;
 
-namespace CountingCharOccurences
-{
-    internal class Program
-    {
-        static void Main(string[] args)
-        {
-            BenchmarkRunner.Run<CountChars>();
-        }
-    }
-}
+BenchmarkRunner.Run<CountChars>();

strings-csharp/CountingCharOccurences/Test/CountSubstringsAndFrequenciesTest.cs

@@ -0,0 +1,52 @@
+using CountingCharOccurences;
+
+namespace Test
+{
+    public class CountSubstringsAndFrequenciesTest
+    {
+        private static readonly CountSubstringsAndFrequencies _counter = new CountSubstringsAndFrequencies();
+
+        [Fact]
+        public void WhenCountSubstringNonOverlappingThenMatchesDoNotOverlap()
+        {
+            string main = "aaaa";
+            string toFind = "aa";
+
+            int actual = _counter.CountSubstringNonOverlapping(main, toFind);
+
+            Assert.Equal(2, actual);
+        }
+
+        [Fact]
+        public void WhenCountSubstringOverlappingThenMatchesOverlap()
+        {
+            string main = "aaaa";
+            string toFind = "aa";
+
+            int actual = _counter.CountSubstringOverlapping(main, toFind);
+
+            Assert.Equal(3, actual);
+        }
+
+        [Fact]
+        public void WhenCountEveryCharUsingLinqThenReturnFrequencyOfEachChar()
+        {
+            string main = "hello world";
+
+            var actual = _counter.CountEveryCharUsingLinq(main);
+
+            Assert.Equal(3, actual['l']);
+            Assert.Equal(2, actual['o']);
+        }
+
+        [Fact]
+        public void WhenCountEveryCharUsingLoopThenReturnSameFrequenciesAsLinq()
+        {
+            string main = "hello world";
+
+            var actual = _counter.CountEveryCharUsingLoop(main);
+
+            Assert.Equal(_counter.CountEveryCharUsingLinq(main), actual);
+        }
+    }
+}

strings-csharp/CountingCharOccurences/Test/Test.cs

@@ -50,6 +50,17 @@ public void WhenSearchCharUsingIndexThenReturnNumberOfOccurences()
             Assert.Equal(2, actual);
         }
 
+        [Fact]
+        public void WhenSearchCharWithAdjacentOccurencesThenReturnNumberOfOccurences()
+        {
+            string main = "LLama LLama";
+            char toFind = 'L';
+
+            int actual = _countChars.CountCharsUsingIndex(main, toFind);
+
+            Assert.Equal(4, actual);
+        }
+
         [Fact]
         public void WhenSearchCharUsingForThenReturnNumberOfOccurences()
         {

strings-csharp/CountingCharOccurences/Test/Test.csproj

@@ -1,21 +1,21 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.3.2" />
-    <PackageReference Include="xunit" Version="2.4.2" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.10.1" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="4.0.0">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
-    <PackageReference Include="coverlet.collector" Version="3.1.2">
+    <PackageReference Include="coverlet.collector" Version="10.0.1">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>