From 89459f9cfcd71c0ff9b459c679dea58dd0308836 Mon Sep 17 00:00:00 2001 From: David Hackbarth Date: Mon, 22 Sep 2025 12:47:22 +0200 Subject: [PATCH] add pointer add smart pointer --- CPlusPlus/CPlusPlus.sln | 14 ++ CPlusPlus/Pointer/Pointer.vcxproj | 188 ++++++++++++++++++++++ CPlusPlus/Pointer/Pointer.vcxproj.filters | 30 ++++ CPlusPlus/Pointer/functions.cpp | 18 +++ CPlusPlus/Pointer/functions.h | 5 + CPlusPlus/Pointer/main.cpp | 69 ++++++++ 6 files changed, 324 insertions(+) create mode 100644 CPlusPlus/Pointer/Pointer.vcxproj create mode 100644 CPlusPlus/Pointer/Pointer.vcxproj.filters create mode 100644 CPlusPlus/Pointer/functions.cpp create mode 100644 CPlusPlus/Pointer/functions.h create mode 100644 CPlusPlus/Pointer/main.cpp diff --git a/CPlusPlus/CPlusPlus.sln b/CPlusPlus/CPlusPlus.sln index 979c04a..5c310a0 100644 --- a/CPlusPlus/CPlusPlus.sln +++ b/CPlusPlus/CPlusPlus.sln @@ -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 diff --git a/CPlusPlus/Pointer/Pointer.vcxproj b/CPlusPlus/Pointer/Pointer.vcxproj new file mode 100644 index 0000000..dc9cb59 --- /dev/null +++ b/CPlusPlus/Pointer/Pointer.vcxproj @@ -0,0 +1,188 @@ + + + + + Debug + Win32 + + + Release + Win32 + + + Debug + x64 + + + Release + x64 + + + Debug + ARM64 + + + Release + ARM64 + + + + 17.0 + Win32Proj + {2a8a01e9-d0e6-4d69-83ee-d05c81829edb} + Pointer + 10.0 + + + + Application + true + v143 + Unicode + + + Application + false + v143 + true + Unicode + + + Application + true + v143 + Unicode + + + Application + false + v143 + true + Unicode + + + Application + true + v143 + Unicode + + + Application + false + v143 + true + Unicode + + + + + + + + + + + + + + + + + + + + + + + + + + + + Level3 + true + WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions) + true + + + Console + true + + + + + Level3 + true + true + true + WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions) + true + + + Console + true + + + + + Level3 + true + _DEBUG;_CONSOLE;%(PreprocessorDefinitions) + true + + + Console + true + + + + + Level3 + true + true + true + NDEBUG;_CONSOLE;%(PreprocessorDefinitions) + true + + + Console + true + + + + + Level3 + true + _DEBUG;_CONSOLE;%(PreprocessorDefinitions) + true + + + Console + true + + + + + Level3 + true + true + true + NDEBUG;_CONSOLE;%(PreprocessorDefinitions) + true + + + Console + true + + + + + + + + + + + + + \ No newline at end of file diff --git a/CPlusPlus/Pointer/Pointer.vcxproj.filters b/CPlusPlus/Pointer/Pointer.vcxproj.filters new file mode 100644 index 0000000..54bcd79 --- /dev/null +++ b/CPlusPlus/Pointer/Pointer.vcxproj.filters @@ -0,0 +1,30 @@ + + + + + {4FC737F1-C7A5-4376-A066-2A32D752A2FF} + cpp;c;cc;cxx;c++;cppm;ixx;def;odl;idl;hpj;bat;asm;asmx + + + {93995380-89BD-4b04-88EB-625FBE52EBFB} + h;hh;hpp;hxx;h++;hm;inl;inc;ipp;xsd + + + {67DA6AB6-F800-4c08-8B7A-83BB121AAD01} + rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe;resx;tiff;tif;png;wav;mfcribbon-ms + + + + + Source Files + + + Source Files + + + + + Header Files + + + \ No newline at end of file diff --git a/CPlusPlus/Pointer/functions.cpp b/CPlusPlus/Pointer/functions.cpp new file mode 100644 index 0000000..99a39ed --- /dev/null +++ b/CPlusPlus/Pointer/functions.cpp @@ -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; +} \ No newline at end of file diff --git a/CPlusPlus/Pointer/functions.h b/CPlusPlus/Pointer/functions.h new file mode 100644 index 0000000..d509cd5 --- /dev/null +++ b/CPlusPlus/Pointer/functions.h @@ -0,0 +1,5 @@ +#pragma once + +void changeInteger(int n); +void changeIntegerPerPointer(int* pN); +void changeIntegerPerReference(int& n); \ No newline at end of file diff --git a/CPlusPlus/Pointer/main.cpp b/CPlusPlus/Pointer/main.cpp new file mode 100644 index 0000000..dc3d6f7 --- /dev/null +++ b/CPlusPlus/Pointer/main.cpp @@ -0,0 +1,69 @@ +#include +#include // 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 pNumber2 = make_unique(10); + *pNumber2 = 100; + //unique_ptr pNumber3 = pNumber2; // compiler error - you can't create a copy of an unique pointer + unique_ptr pNumber4 = make_unique(*pNumber2); + + shared_ptr pNumber5 = make_shared(10); + shared_ptr pNumber6 = pNumber5; + *pNumber6 = 100; + + pNumber5.reset(); + + weak_ptr 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 pTmpSharedPointer = pNumber7.lock(); + *pTmpSharedPointer = 10000; + } + + pNumber6.reset(); + shared_ptr pTmpSharedPointer2 = pNumber7.lock(); + if (pTmpSharedPointer2 != nullptr) *pTmpSharedPointer2 = 10; // smart pointer are no guarantee for a valid object behind the pointer + + return 0; +} \ No newline at end of file