add pointer

add smart pointer
2025-09-22 12:47:22 +02:00
parent 2dc23a4efc
commit 89459f9cfc
6 changed files with 324 additions and 0 deletions
@@ -11,6 +11,8 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Classes", "Classes\Classes.
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Collections", "Collections\Collections.vcxproj", "{34173AE8-DCD5-46FE-AF4D-85FB110721BA}"
 EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Pointer", "Pointer\Pointer.vcxproj", "{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|ARM64 = Debug|ARM64
@@ -69,6 +71,18 @@ Global
 		{34173AE8-DCD5-46FE-AF4D-85FB110721BA}.Release|x64.Build.0 = Release|x64
 		{34173AE8-DCD5-46FE-AF4D-85FB110721BA}.Release|x86.ActiveCfg = Release|Win32
 		{34173AE8-DCD5-46FE-AF4D-85FB110721BA}.Release|x86.Build.0 = Release|Win32
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Debug|ARM64.ActiveCfg = Debug|ARM64
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Debug|ARM64.Build.0 = Debug|ARM64
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Debug|x64.ActiveCfg = Debug|x64
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Debug|x64.Build.0 = Debug|x64
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Debug|x86.ActiveCfg = Debug|Win32
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Debug|x86.Build.0 = Debug|Win32
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Release|ARM64.ActiveCfg = Release|ARM64
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Release|ARM64.Build.0 = Release|ARM64
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Release|x64.ActiveCfg = Release|x64
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Release|x64.Build.0 = Release|x64
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Release|x86.ActiveCfg = Release|Win32
+		{2A8A01E9-D0E6-4D69-83EE-D05C81829EDB}.Release|x86.Build.0 = Release|Win32
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -0,0 +1,188 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|Win32">
+      <Configuration>Debug</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|ARM64">
+      <Configuration>Debug</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|ARM64">
+      <Configuration>Release</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <VCProjectVersion>17.0</VCProjectVersion>
+    <Keyword>Win32Proj</Keyword>
+    <ProjectGuid>{2a8a01e9-d0e6-4d69-83ee-d05c81829edb}</ProjectGuid>
+    <RootNamespace>Pointer</RootNamespace>
+    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>true</UseDebugLibraries>
+    <PlatformToolset>v143</PlatformToolset>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>false</UseDebugLibraries>
+    <PlatformToolset>v143</PlatformToolset>
+    <WholeProgramOptimization>true</WholeProgramOptimization>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>true</UseDebugLibraries>
+    <PlatformToolset>v143</PlatformToolset>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>false</UseDebugLibraries>
+    <PlatformToolset>v143</PlatformToolset>
+    <WholeProgramOptimization>true</WholeProgramOptimization>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|ARM64'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>true</UseDebugLibraries>
+    <PlatformToolset>v143</PlatformToolset>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>false</UseDebugLibraries>
+    <PlatformToolset>v143</PlatformToolset>
+    <WholeProgramOptimization>true</WholeProgramOptimization>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+  </ImportGroup>
+  <ImportGroup Label="Shared">
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|ARM64'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <PropertyGroup Label="UserMacros" />
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <ClCompile>
+      <WarningLevel>Level3</WarningLevel>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
+    <ClCompile>
+      <WarningLevel>Level3</WarningLevel>
+      <FunctionLevelLinking>true</FunctionLevelLinking>
+      <IntrinsicFunctions>true</IntrinsicFunctions>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
+    <ClCompile>
+      <WarningLevel>Level3</WarningLevel>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <ClCompile>
+      <WarningLevel>Level3</WarningLevel>
+      <FunctionLevelLinking>true</FunctionLevelLinking>
+      <IntrinsicFunctions>true</IntrinsicFunctions>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|ARM64'">
+    <ClCompile>
+      <WarningLevel>Level3</WarningLevel>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'">
+    <ClCompile>
+      <WarningLevel>Level3</WarningLevel>
+      <FunctionLevelLinking>true</FunctionLevelLinking>
+      <IntrinsicFunctions>true</IntrinsicFunctions>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemGroup>
+    <ClCompile Include="functions.cpp" />
+    <ClCompile Include="main.cpp" />
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="functions.h" />
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
+</Project>
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup>
+    <Filter Include="Source Files">
+      <UniqueIdentifier>{4FC737F1-C7A5-4376-A066-2A32D752A2FF}</UniqueIdentifier>
+      <Extensions>cpp;c;cc;cxx;c++;cppm;ixx;def;odl;idl;hpj;bat;asm;asmx</Extensions>
+    </Filter>
+    <Filter Include="Header Files">
+      <UniqueIdentifier>{93995380-89BD-4b04-88EB-625FBE52EBFB}</UniqueIdentifier>
+      <Extensions>h;hh;hpp;hxx;h++;hm;inl;inc;ipp;xsd</Extensions>
+    </Filter>
+    <Filter Include="Resource Files">
+      <UniqueIdentifier>{67DA6AB6-F800-4c08-8B7A-83BB121AAD01}</UniqueIdentifier>
+      <Extensions>rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe;resx;tiff;tif;png;wav;mfcribbon-ms</Extensions>
+    </Filter>
+  </ItemGroup>
+  <ItemGroup>
+    <ClCompile Include="main.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="functions.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="functions.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+  </ItemGroup>
+</Project>
@@ -0,0 +1,18 @@
+#include "functions.h"
+
+void changeInteger(int n)
+{
+	n *= 2;
+}
+
+void changeIntegerPerPointer(int* pN)
+{
+	if (pN == nullptr) return; // BE CAREFUL - a pointer can always be nullptr
+
+	*pN *= 2;
+}
+
+void changeIntegerPerReference(int& n)
+{
+	n *= 2;
+}
@@ -0,0 +1,5 @@
+#pragma once
+
+void changeInteger(int n);
+void changeIntegerPerPointer(int* pN);
+void changeIntegerPerReference(int& n);
@@ -0,0 +1,69 @@
+#include <iostream>
+#include <memory> // smart pointer header
+
+#include "functions.h"
+
+using namespace std;
+
+int main()
+{
+	// general
+	int* pNumber = nullptr;
+	pNumber = new int(0);
+
+	cout << "pNumber: " << pNumber << endl;
+	cout << "*pNumber: " << *pNumber << endl;
+	cout << "size of pointer: " << sizeof(pNumber) << endl;
+	cout << "size of *pointer: " << sizeof(*pNumber) << endl;
+
+	*pNumber = 567;
+
+	//pNumber = new int(0); // BAD BAD - Memory Leak, because we overriding an existing pointer address with a new one
+
+	// here are 100s line of code OR at different position
+
+	if (pNumber != nullptr)
+	{
+		delete pNumber;
+		pNumber = nullptr;
+	}
+
+	// pointer as references
+	int number = 10;
+	changeInteger(number);
+	changeIntegerPerPointer(&number);
+	changeIntegerPerPointer(pNumber);
+	changeIntegerPerReference(number);
+	//changeIntegerPerReference(10); // doesn't work, because you need an existing & initialized variable for a reference
+
+	// smart pointer
+	// unique_ptr - only one owner exist for the object
+	// shared_ptr - can have multiple owners
+	// weak_ptr - is a loose connection to a shared_ptr
+
+	unique_ptr<int> pNumber2 = make_unique<int>(10);
+	*pNumber2 = 100;
+	//unique_ptr<int> pNumber3 = pNumber2; // compiler error - you can't create a copy of an unique pointer
+	unique_ptr<int> pNumber4 = make_unique<int>(*pNumber2);
+
+	shared_ptr<int> pNumber5 = make_shared<int>(10);
+	shared_ptr<int> pNumber6 = pNumber5;
+	*pNumber6 = 100;
+
+	pNumber5.reset();
+
+	weak_ptr<int> pNumber7 = pNumber6;
+	//*pNumber7 = 1000; // compiler error, because a weak pointer has no direct access to the shared pointer, you have to create a shared pointer object
+
+	if (!pNumber7.expired())
+	{
+		shared_ptr<int> pTmpSharedPointer = pNumber7.lock();
+		*pTmpSharedPointer = 10000;
+	}
+
+	pNumber6.reset();
+	shared_ptr<int> pTmpSharedPointer2 = pNumber7.lock();
+	if (pTmpSharedPointer2 != nullptr) *pTmpSharedPointer2 = 10; // smart pointer are no guarantee for a valid object behind the pointer
+
+	return 0;
+}