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pkulikovBillWagner
pkulikov
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BillWagner
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Added snippets for the pointer related operators (#916)
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‎snippets/csharp/language-reference/operators/PointerOperators.cs‎

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using System;
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namespace operators
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{
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public static class PointerOperators
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{
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public static void Examples()
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{
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AddressOf();
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PointerIndirection();
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PointerMemberAccessExample.Main();
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PointerElementAccess();
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PointerAddition();
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PointerSubtraction();
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Increment();
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}
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private static void AddressOf()
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{
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// <SnippetAddressOf>
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unsafe
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{
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int number = 27;
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int* pointerToNumber = &number;
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Console.WriteLine($"Value of the variable: {number}");
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Console.WriteLine($"Address of the variable: {(long)pointerToNumber:X}");
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}
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// Output is similar to:
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// Value of the variable: 27
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// Address of the variable: 6C1457DBD4
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// </SnippetAddressOf>
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}
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private static void AddressOfFixed()
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{
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// <SnippetAddressOfFixed>
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unsafe
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{
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byte[] bytes = { 1, 2, 3 };
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fixed (byte* pointerToFirst = &bytes[0])
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{
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// The address stored in pointerToFirst
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// is valid only inside this fixed statement block.
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}
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}
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// </SnippetAddressOfFixed>
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}
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private static void PointerIndirection()
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{
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// <SnippetPointerIndirection>
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unsafe
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{
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char letter = 'A';
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char* pointerToLetter = &letter;
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Console.WriteLine($"Value of the `letter` variable: {letter}");
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Console.WriteLine($"Address of the `letter` variable: {(long)pointerToLetter:X}");
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*pointerToLetter = 'Z';
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Console.WriteLine($"Value of the `letter` variable after update: {letter}");
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}
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// Output is similar to:
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// Value of the `letter` variable: A
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// Address of the `letter` variable: DCB977DDF4
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// Value of the `letter` variable after update: Z
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// </SnippetPointerIndirection>
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}
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// <SnippetMemberAccess>
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public struct Coords
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{
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public int X;
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public int Y;
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public override string ToString() => $"({X}, {Y})";
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}
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public class PointerMemberAccessExample
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{
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public static unsafe void Main()
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{
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Coords coords;
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Coords* p = &coords;
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p->X = 3;
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p->Y = 4;
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Console.WriteLine(p->ToString()); // output: (3, 4)
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}
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}
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// </SnippetMemberAccess>
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private static void PointerElementAccess()
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{
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// <SnippetElementAccess>
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unsafe
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{
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char* pointerToChars = stackalloc char[123];
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for (int i = 65; i < 123; i++)
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{
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pointerToChars[i] = (char)i;
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}
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Console.Write("Uppercase letters: ");
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for (int i = 65; i < 91; i++)
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{
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Console.Write(pointerToChars[i]);
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}
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}
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// Output:
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// Uppercase letters: ABCDEFGHIJKLMNOPQRSTUVWXYZ
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// </SnippetElementAccess>
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Console.WriteLine();
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}
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private static void PointerAddition()
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{
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// <SnippetAddNumber>
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unsafe
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{
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const int Count = 3;
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int[] numbers = new int[Count] { 10, 20, 30 };
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fixed (int* pointerToFirst = &numbers[0])
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{
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int* pointerToLast = pointerToFirst + (Count - 1);
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Console.WriteLine($"Value {*pointerToFirst} at address {(long)pointerToFirst}");
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Console.WriteLine($"Value {*pointerToLast} at address {(long)pointerToLast}");
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}
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}
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// Output is similar to:
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// Value 10 at address 1818345918136
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// Value 30 at address 1818345918144
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// </SnippetAddNumber>
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}
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private static void PointerSubtraction()
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{
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// <SnippetSubtractPointers>
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unsafe
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{
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int* numbers = stackalloc int[] { 0, 1, 2, 3, 4, 5 };
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int* p1 = &numbers[1];
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int* p2 = &numbers[5];
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Console.WriteLine(p2 - p1); // output: 4
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}
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// </SnippetSubtractPointers>
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}
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private static void Increment()
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{
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// <SnippetIncrement>
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unsafe
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{
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int* numbers = stackalloc int[] { 0, 1, 2 };
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int* p1 = &numbers[0];
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int* p2 = p1;
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Console.WriteLine($"Before operation: p1 - {(long)p1}, p2 - {(long)p2}");
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Console.WriteLine($"Postfix increment of p1: {(long)(p1++)}");
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Console.WriteLine($"Prefix increment of p2: {(long)(++p2)}");
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Console.WriteLine($"After operation: p1 - {(long)p1}, p2 - {(long)p2}");
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}
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// Output is similar to
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// Before operation: p1 - 816489946512, p2 - 816489946512
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// Postfix increment of p1: 816489946512
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// Prefix increment of p2: 816489946516
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// After operation: p1 - 816489946516, p2 - 816489946516
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// </SnippetIncrement>
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}
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}
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}

‎snippets/csharp/language-reference/operators/Program.cs‎

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@@ -30,12 +30,12 @@ static void Main(string[] args)
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MemberAccessOperators.Examples();
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Console.WriteLine();
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Console.WriteLine("============== + operator examples =============");
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AdditionExamples.Examples();
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Console.WriteLine("======= Pointer related operators examples =====");
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PointerOperators.Examples();
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Console.WriteLine();
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Console.WriteLine("============== & operator examples =============");
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AndOperatorExamples.Examples();
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Console.WriteLine("============== + operator examples =============");
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AdditionExamples.Examples();
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Console.WriteLine();
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Console.WriteLine("============== = operator examples =============");

‎snippets/csharp/language-reference/operators/operators.csproj‎

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<PropertyGroup>
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<LangVersion>7.3</LangVersion>
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<StartupObject>operators.Program</StartupObject>
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<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
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</PropertyGroup>
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</Project>

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