Added the solution to Lesson 2

Author: MakersF

.gitignore

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+build/

Lesson 2/Activity 4/README.md

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 # BeginningCPlusPlus
+
+Compile the activity by running `compile.bat`.

Lesson 2/Activity 4/compile.bat

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+:: Folder where the built objects are stored
+mkdir build
+
+:: Build log.cpp, but do not link
+:: /c means compile only, do not link
+:: /Fo specifies the folder where to put the output
+cl /EHsc /c /Fobuild/ log.cpp
+
+:: Build main.cpp, but do not link
+:: /I adds a folder to the folders where to look for includes.
+:: We add the current folder because we are including log.h
+cl /EHsc /c /Fobuild/ /I . main.cpp
+
+:: Link the two object files together
+LINK build\log.obj build\main.obj /OUT:build\main.exe
+
+:: You can not run the program at build\main.exe

Lesson 2/Activity 4/log.cpp

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+// The header iostream contains std::cout and std::endl
+#include <iostream>
+
+// Define the log function. We already declared it in the .h file
+void log() {
+	std::cout << "Error!" << std::endl;
+}

Lesson 2/Activity 4/log.h

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+// Declare the log function, which takes no arguments and returns nothing
+void log();

Lesson 2/Activity 4/main.cpp

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+// The loh.h header declares the log function
+#include <log.h>
+
+// main is the entry point of the program: it is called when the program starts
+int main() {
+	log(); // call the function log which is defined in the loh.h header
+}

Lesson 2/Activity 5/compile.bat

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+:: Folder where the built objects are stored
+mkdir build
+
+:: Build and link main.cpp
+cl /EHsc /Fobuild/ /Febuild/ main.cpp
+
+:: You can not run the program at build\main.exe

Lesson 2/Activity 5/main.cpp

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+#include <iostream>
+
+// global variables accessible by the whole file.
+// Since we don't want to modify them, we mark them with const.
+const int POSITION = 10;
+const int ALREADY_COMPUTED = 3;
+
+// Define and declare the function
+void print_tenth_fibonacci() {
+    // Local variables.
+    // They don't have to be defined at the top of the function!
+	int n_1 = 1;
+	int n_2 = 0;
+	int current = n_1 + n_2;
+    // We can access the global variables from inside the function
+	for(int i = ALREADY_COMPUTED; i <= POSITION; ++i) {
+		current = n_1 + n_2;
+		n_2 = n_1;
+		n_1 = current;
+	}
+ 	std::cout << current << std::endl;
+}
+
+int main() {
+	print_tenth_fibonacci();
+}

Lesson 2/Activity 6/compile.bat

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+:: Folder where the built objects are stored
+mkdir build
+
+:: Build and link main.cpp
+cl /EHsc /Fobuild/ /Febuild/ main.cpp
+
+:: You can not run the program at build\main.exe

Lesson 2/Activity 6/main.cpp

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+// std::array<Type, Number of Elements> is defined in the array header
+#include <array>
+#include <iostream>
+
+// The size of the arguments is small: take by value
+int sum(int a, int b)
+{
+	return a + b;
+}
+
+// We need to modify the result, so we need to use non-const references for the arrays
+int& getMaxOf(std::array<int, 10>& array1, std::array<int, 10>& array2, int index) {
+	if (array1[index] >= array2[index]) {
+		return array1[index];
+	} else {
+		return array2[index];
+	}
+}
+
+int main() {
+    // We pass by value, so we can use temporary values safely
+    std::cout << "sum(2, 3) = " << sum(2, 3) << std::endl;
+
+    std::array<int, 10> sorted = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
+    std::array<int, 10> reversed = {10, 9, 8, 7, 6, 5, 4, 3, 2, 1};
+    std::cout << "sorted[0] = " << sorted[0] << "\n" << "reversed[0] = " << reversed[0] << std::endl;
+
+    // We want to modify the element, so we need to make sure we take the result as reference.
+    // If we were to return the result as a value, when we modify it it will not propagate
+    // to the original element
+    int& element = getMaxOf(sorted, reversed, 0);
+    std::cout << "Max: " << element << std::endl;
+    element = 0;
+    std::cout << "sorted[0] = " << sorted[0] << "\n" << "reversed[0] = " << reversed[0] << std::endl;
+    std::cout << "The original value has been updated though the reference!" << std::endl;
+
+    // Note: we are taking by value. This creates a new local copy, and changes to it will not modify
+    // the original value
+    int value = getMaxOf(sorted, reversed, 0);
+    value = 10;
+    std::cout << "sorted[0] = " << sorted[0] << "\n" << "reversed[0] = " << reversed[0] << std::endl;
+    std::cout << "The original value has *not* been updated though the value!" << std::endl;
+}

Lesson 2/Exercise 6/README.md renamed to Lesson 2/Activity 7/README.md

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+:: Folder where the built objects are stored
+mkdir build
+
+:: Build and link main.cpp
+cl /EHsc /Fobuild/ /Febuild/ main.cpp
+
+:: You can not run the program at build\main.exe

Lesson 2/Activity 7/compile.bat

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+// Open a namespace called 'a'
+namespace a {
+
+// Define a function named 'a' inside the namespace 'a'
+void a() {}
+
+// The namespace 'a' is closed here
+}
+
+// Open a namespace called 'b'
+namespace b {
+
+// Define a function named 'b' inside the namespace 'b'
+void b() {}
+
+// The namespace 'b' is closed here
+}
+
+// Open an anonymous namespace
+namespace {
+
+// Define a function named 'c' inside the anonymous namespace
+void c() {
+    // To call functions inside a namespace different from the current functions you
+    // need to put the name of the namespace first.
+	a::a();
+	using b::b;
+	b();
+}
+
+// The anonymous namespace is closed here
+}
+
+// Here we are outisde of any namespace
+
+int main() {
+    // The c() function is callable from outside the anonymous namespace.
+    c();
+    b::b();
+}

Lesson 2/Activity 7/main.cpp

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+# BeginningCPlusPlus

Lesson 2/Activity 8/README.md

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+:: Folder where the built objects are stored
+mkdir build
+
+:: Build and link main.cpp
+cl /EHsc /Fobuild/ /Febuild/ main.cpp
+
+:: You can not run the program at build\main.exe

Lesson 2/Activity 8/compile.bat

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+#include <iostream>
+
+int square(int x) {
+	return x * x;
+}
+
+float square(float x) {
+	return x * x;
+}
+
+int main() {
+    // The overload which takes float is called
+	std::cout << square(1.5f) << std::endl;
+    // The overload which takes int is called
+	std::cout << square(1) << std::endl;
+}

Lesson 2/Activity 8/main.cpp

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+:: Folder where the built objects are stored
+mkdir build
+
+:: Build and link main.cpp
+cl /EHsc /Fobuild/ /Febuild/ main.cpp
+
+:: You can not run the program at build\main.exe

Lesson 2/Exercise 4/compile.bat

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+#include <iostream>
+
+// Define and declares the function.
+// The parameter is taken by value: a new copy will be created.
+// Changes inside the function will not be reflected in the value
+// used when calling the function
+void byvalue_age_in_5_years(int age) {
+    // Age here is a new copy. We increment it by 5 but then it's lifetime terminates.
+	age += 5;
+}
+
+int main() {
+	int a = 95;
+	byvalue_age_in_5_years(a);
+    // a is not modified because it was accepted by value
+	std::cout << "Value: " << a; // Prints 95
+}

Lesson 2/Exercise 4/main.cpp

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+:: Folder where the built objects are stored
+mkdir build
+
+:: Build and link main.cpp
+cl /EHsc /Fobuild/ /Febuild/ main.cpp
+
+:: You can not run the program at build\main.exe

Lesson 2/Exercise 5/compile.bat

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+#include <iostream>
+
+// The parameter is taken by reference.
+// Changes inside the function will be reflected in the value of the caller
+void byvalue_age_in_5_years(int& age) {
+	age += 5;
+}
+
+int main() {
+	int a = 95;
+	byvalue_age_in_5_years(a);
+	// a has been incremented by the function, because it operated on a reference
+	// to the local variable
+	std::cout << "Value: " << a; // Prints 100
+}