Started a cmake tutorial

Step2/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.10)
+
+# set the project name and version
+project(Tutorial VERSION 1.0)
+
+# specify the C++ standard
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
+
+# configure a header file to pass some of the CMake settings
+# to the source code
+configure_file(TutorialConfig.h.in TutorialConfig.h)
+
+# TODO 2: Use add_subdirectory() to add MathFunctions to this project
+
+# add the executable
+add_executable(Tutorial tutorial.cxx)
+
+# TODO 3: Use target_link_libraries to link the library to our executable
+
+# TODO 4: Add MathFunctions to Tutorial's target_include_directories()
+# Hint: ${PROJECT_SOURCE_DIR} is a path to the project source. AKA This folder!
+
+# add the binary tree to the search path for include files
+# so that we will find TutorialConfig.h
+target_include_directories(Tutorial PUBLIC
+                           "${PROJECT_BINARY_DIR}"
+                           )

Step2/MathFunctions/CMakeLists.txt

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+# TODO 14: Remove mysqrt.cxx from the list of sources
+
+# TODO 1: Add a library called MathFunctions with sources MathFunctions.cxx
+# and mysqrt.cxx
+# Hint: You will need the add_library command
+
+# TODO 7: Create a variable USE_MYMATH using option and set default to ON
+
+# TODO 8: If USE_MYMATH is ON, use target_compile_definitions to pass
+# USE_MYMATH as a precompiled definition to our source files
+
+# TODO 12: When USE_MYMATH is ON, add a library for SqrtLibrary with
+# source mysqrt.cxx
+
+# TODO 13: When USE_MYMATH is ON, link SqrtLibrary to the MathFunctions Library

Step2/MathFunctions/MathFunctions.cxx

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+#include "MathFunctions.h"
+
+// TODO 11: include cmath
+
+// TODO 10: Wrap the mysqrt include in a precompiled ifdef based on USE_MYMATH
+#include "mysqrt.h"
+
+namespace mathfunctions {
+double sqrt(double x)
+{
+  // TODO 9: If USE_MYMATH is defined, use detail::mysqrt.
+  // Otherwise, use std::sqrt.
+  return detail::mysqrt(x);
+}
+}

Step2/MathFunctions/MathFunctions.h

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+#pragma once
+
+namespace mathfunctions {
+double sqrt(double x);
+}

Step2/MathFunctions/mysqrt.cxx

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+#include "mysqrt.h"
+
+#include <iostream>
+
+namespace mathfunctions {
+namespace detail {
+// a hack square root calculation using simple operations
+double mysqrt(double x)
+{
+  if (x <= 0) {
+    return 0;
+  }
+
+  double result = x;
+
+  // do ten iterations
+  for (int i = 0; i < 10; ++i) {
+    if (result <= 0) {
+      result = 0.1;
+    }
+    double delta = x - (result * result);
+    result = result + 0.5 * delta / result;
+    std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
+  }
+  return result;
+}
+}
+}

Step2/MathFunctions/mysqrt.h

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+#pragma once
+
+namespace mathfunctions {
+namespace detail {
+double mysqrt(double x);
+}
+}

Step2/TutorialConfig.h.in

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+// the configured options and settings for Tutorial
+#define Tutorial_VERSION_MAJOR @Tutorial_VERSION_MAJOR@
+#define Tutorial_VERSION_MINOR @Tutorial_VERSION_MINOR@

Step2/tutorial.cxx

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+// A simple program that computes the square root of a number
+#include <cmath>
+#include <iostream>
+#include <string>
+
+// TODO 5: Include MathFunctions.h
+#include "TutorialConfig.h"
+
+int main(int argc, char* argv[])
+{
+  if (argc < 2) {
+    // report version
+    std::cout << argv[0] << " Version " << Tutorial_VERSION_MAJOR << "."
+              << Tutorial_VERSION_MINOR << std::endl;
+    std::cout << "Usage: " << argv[0] << " number" << std::endl;
+    return 1;
+  }
+
+  // convert input to double
+  const double inputValue = std::stod(argv[1]);
+
+  // TODO 6: Replace sqrt with mathfunctions::sqrt
+
+  // calculate square root
+  const double outputValue = sqrt(inputValue);
+  std::cout << "The square root of " << inputValue << " is " << outputValue
+            << std::endl;
+  return 0;
+}