Examples for String.Copy alternatives (#949)

Author: Ron Petrusha

snippets/csharp/api/system/string/copy/Program.cs

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+using System;
+using System.Runtime.InteropServices;
+
+namespace copy
+{
+    class Program
+    {
+        static void Main()
+        {
+            PerformStringOperation();
+            Console.WriteLine("---");
+            UseMutableBuffer();
+            Console.WriteLine("---");
+            UseUnmanaged();
+        }
+
+        private static void PerformStringOperation()
+        {
+            // <Snippet1>
+            var original = "This is a sentence. This is a second sentence.";
+            var sentence1 = original.Substring(0, original.IndexOf(".") + 1);
+            Console.WriteLine(original);
+            Console.WriteLine(sentence1);
+            // The example displays the following output:
+            //    This is a sentence. This is a second sentence.
+            //    This is a sentence.            
+            // </Snippet1>
+        }
+
+        // <Snippet2>
+        private static void UseMutableBuffer()
+        {
+            var original = "This is a sentence. This is a second sentence.";
+            var chars = original.ToCharArray();
+            var span = new Span<char>(chars);
+            var slice = span.Slice(span.IndexOf('.'), 3);
+            slice = MergeSentence(slice);
+            Console.WriteLine($"Original string: {original}");
+            Console.WriteLine($"Modified string: {span.ToString()}");
+
+            static Span<char> MergeSentence(Span<char> span)
+            {
+                if (span.Length == 0) return Span<char>.Empty;
+
+                span[0] = ';';
+                span[2] = Char.ToLower(span[2]);
+                return span;
+            }
+        }
+        // The example displays the following output:
+        //    Original string: This is a sentence. This is a second sentence.
+        //    Modified string: This is a sentence; this is a second sentence.        
+        // </Snippet2>
+
+        // <Snippet3>
+        private static void UseUnmanaged()
+        {
+            var original = "This is a single sentence.";
+            var len = original.Length; 
+            var ptr = Marshal.StringToHGlobalUni(original);
+            string result;
+            unsafe 
+            {
+                char *ch = (char *) ptr.ToPointer();
+                while (len-- > 0)
+                {
+                    char c = Convert.ToChar(Convert.ToUInt16(*ch) + 1);
+                    *ch++ = c;
+                } 
+                result = Marshal.PtrToStringUni(ptr);
+                Marshal.FreeHGlobal(ptr);
+            }
+            Console.WriteLine($"Original string: {original}");
+            Console.WriteLine($"String from interop: '{result}'");
+        }
+        // The example displays the following output:
+        //    Original string: This is a single sentence.
+        //    String from interop: 'Uijt!jt!b!tjohmf!tfoufodf/'      
+        // </Snippet3>
+    }
+}
+

snippets/csharp/api/system/string/copy/copy.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <LangVersion>8.0</LangVersion>
+    <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
+  </PropertyGroup>
+
+</Project>

snippets/visualbasic/api/system/string/copy/Program.vb

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+Imports System
+Imports System.Runtime.CompilerServices
+Imports System.Text
+
+Module Program
+    Sub Main()
+        PerformStringOperation()
+        Console.WriteLine("---")
+        UseMutableBuffer()
+        Console.WriteLine("---")
+    End Sub
+
+    Private Sub PerformStringOperation()
+        ' <Snippet1>
+        Dim original = "This is a sentence. This is a second sentence."
+        Dim sentence1 = original.Substring(0, original.IndexOf(".") + 1)
+        Console.WriteLine(original)
+        Console.WriteLine(sentence1)
+        ' The example displays the following output:
+        '    This is a sentence. This is a second sentence.
+        '    This is a sentence.            
+        ' </Snippet1>
+    End Sub
+
+    ' <Snippet2>
+    Private Sub UseMutableBuffer()
+        Dim original = "This is a sentence. This is a second sentence."
+        Dim sb = new StringBuilder(original)
+        Dim index = original.IndexOf(".")
+        sb(index) = ";"
+        sb(index + 2) = Char.ToLower(sb(index + 2))
+        Console.WriteLine($"Original string: {original}")
+        Console.WriteLine($"Modified string: {sb.ToString()}")
+    End Sub
+    ' The example displays the following output:
+    '    Original string: This is a sentence. This is a second sentence.
+    '    Modified string: This is a sentence; this is a second sentence.        
+    ' </Snippet2>
+End Module

snippets/visualbasic/api/system/string/copy/copy.vbproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <RootNamespace>copy.vb</RootNamespace>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
+  </PropertyGroup>
+
+</Project>