add forward declaration examples

add class & inheritance examples

CPlusPlus/CPlusPlus.sln

@@ -1,10 +1,14 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 17
-VisualStudioVersion = 17.13.35828.75 d17.13
+VisualStudioVersion = 17.13.35828.75
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "HelloWorld", "HelloWorld\HelloWorld.vcxproj", "{92B0EF46-7137-453A-A7A9-E02D6CE07D8D}"
 EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "forward_declaration", "forward_declaration\forward_declaration.vcxproj", "{2FC9F683-346A-4A58-9294-DB811A2EEC20}"
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Classes", "Classes\Classes.vcxproj", "{467AD272-2BB3-41B7-9B74-7D193D7D2AE9}"
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 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
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 		{92B0EF46-7137-453A-A7A9-E02D6CE07D8D}.Release|x86.Build.0 = Release|Win32
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+		{467AD272-2BB3-41B7-9B74-7D193D7D2AE9}.Release|x86.Build.0 = Release|Win32
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

CPlusPlus/Classes/Classes.vcxproj

@@ -0,0 +1,200 @@
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+    <ClCompile Include="Entity.cpp" />
+    <ClCompile Include="main.cpp" />
+    <ClCompile Include="Monster.cpp" />
+    <ClCompile Include="Ork.cpp" />
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="Entity.h" />
+    <ClInclude Include="ICompareable.h" />
+    <ClInclude Include="Monster.h" />
+    <ClInclude Include="Ork.h" />
+    <ClInclude Include="Vector3.h" />
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+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
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CPlusPlus/Classes/Classes.vcxproj.filters

@@ -0,0 +1,48 @@
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+      <Filter>Source Files</Filter>
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+      <Filter>Source Files</Filter>
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+  </ItemGroup>
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+      <Filter>Header Files</Filter>
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+    <ClInclude Include="Monster.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+    <ClInclude Include="Ork.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+    <ClInclude Include="ICompareable.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+    <ClInclude Include="Vector3.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+  </ItemGroup>
+</Project>

CPlusPlus/Classes/Entity.cpp

@@ -0,0 +1,16 @@
+#include "Entity.h"
+
+Entity::Entity()
+{
+
+}
+
+Entity::Entity(std::string name) : name(name)
+{
+	//this->name = name;
+}
+
+std::string Entity::ToString()
+{
+	return name;
+}

CPlusPlus/Classes/Entity.h

@@ -0,0 +1,14 @@
+#pragma once
+#include <string>
+
+class Entity
+{
+public:
+	Entity();
+	Entity(std::string name);
+
+	virtual std::string ToString();
+
+	std::string name = "";
+
+}; // IMPORTANT: semicolon at the end

CPlusPlus/Classes/ICompareable.h

@@ -0,0 +1,7 @@
+#pragma once
+
+class ICompareable
+{
+public:
+	virtual int Compare(ICompareable* other) = 0;
+};

CPlusPlus/Classes/Monster.cpp

@@ -0,0 +1,18 @@
+#include "Monster.h"
+
+Monster::Monster(int strength) : Entity("My Monster"), _strength(strength)
+{
+	this->name = "My Monster";
+}
+
+std::string Monster::ToString()
+{
+	return name + " " + "(" + std::to_string(_strength) + ")";
+	// TODO: show format
+}
+
+int Monster::Compare(ICompareable* other)
+{
+	// TODO: implement later
+	return 0;
+}

CPlusPlus/Classes/Monster.h

@@ -0,0 +1,16 @@
+#pragma once
+#include "Entity.h"
+#include "ICompareable.h"
+
+class Monster : public Entity, public ICompareable
+{
+public:
+	Monster(int strength);
+
+	virtual void Move() = 0; // abstract (pure virtual method)
+	std::string ToString() override;
+	int Compare(ICompareable* other) override;
+
+protected:
+	int _strength = 0;
+};

CPlusPlus/Classes/Ork.cpp

@@ -0,0 +1,11 @@
+#include "Ork.h"
+
+Ork::Ork() : Monster(10)
+{
+	//this->_strength = 10;
+	this->name = "My Ork";
+}
+
+void Ork::Move()
+{
+}

CPlusPlus/Classes/Ork.h

@@ -0,0 +1,11 @@
+#pragma once
+#include "Monster.h"
+
+class Ork : public Monster
+{
+public:
+	Ork();
+
+	void Move() override;
+};
+

CPlusPlus/Classes/Vector3.h

@@ -0,0 +1,11 @@
+#pragma once
+
+struct Vector3
+{
+	float x;
+	float y;
+	float z;
+
+	Vector3() : x(0.0f), y(0.0f), z(0.0f) {}
+	Vector3(float x, float y, float z) : x(x), y(y), z(z) {}
+};

CPlusPlus/Classes/main.cpp

@@ -0,0 +1,27 @@
+#include <iostream>
+
+#include "Entity.h"
+#include "Ork.h"
+#include "Vector3.h"
+
+using namespace std;
+
+int main()
+{
+	Entity entity; // this is an entity instance
+	entity.name = "My Entity";
+
+	//Monster monster; // can't be instantiated, because Monster is abstract
+
+	Ork ork;
+	ork.name = "My Ork";
+	ork.Move();
+
+	cout << entity.ToString() << endl;
+	cout << ork.ToString() << endl;
+
+	Vector3 position(1.0f, 3.0f, -5.0f);
+	position.y = 0.0f;
+
+	return 0;
+}

CPlusPlus/forward_declaration/forward_declaration.vcxproj

@@ -0,0 +1,194 @@
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CPlusPlus/forward_declaration/forward_declaration.vcxproj.filters

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CPlusPlus/forward_declaration/functions.cpp

@@ -0,0 +1,3 @@
+#include "functions.h"
+
+void functionE() {} // definition

CPlusPlus/forward_declaration/functions.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#ifndef _FUNCTIONS_H_
+#define _FUNCTIONS_H_
+
+void functionE(); // declaration
+//void functionF() {} // defined & declared, linker error when included multiple times
+
+#endif // _FUNCTIONS_H_

CPlusPlus/forward_declaration/main.cpp

@@ -0,0 +1,21 @@
+#include "functions.h"
+
+void functionB() {} // declared & defined
+void functionC(); // declare
+void functionD(); // foward declare
+
+int main()
+{
+	//functionA(); // compiler error, because function is declared & defined after this call
+	functionB(); // no error
+	//functionC(); // linker error, because function is declared, but not defined
+	functionD();
+	functionE();
+	//functionF(); // linker error, because header file was included multiple times with a definition
+
+	return 0;
+}
+
+void functionA() {} // declare & defined
+
+void functionD() {} // definition