hexadecimal: iteration 1

cpp/hexadecimal/CMakeLists.txt

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+# Get the exercise name from the current directory
+get_filename_component(exercise ${CMAKE_CURRENT_SOURCE_DIR} NAME)
+
+# Basic CMake project
+cmake_minimum_required(VERSION 2.8.11)
+
+# Name the project after the exercise
+project(${exercise} CXX)
+
+# Locate Boost libraries: unit_test_framework, date_time and regex
+set(Boost_USE_STATIC_LIBS ON)
+set(Boost_USE_MULTITHREADED ON)
+set(Boost_USE_STATIC_RUNTIME OFF)
+find_package(Boost 1.55 REQUIRED COMPONENTS unit_test_framework date_time regex)
+
+# Enable C++11 features on gcc/clang
+if("${CMAKE_CXX_COMPILER_ID}" MATCHES "(GNU|Clang)")
+    set(CMAKE_CXX_FLAGS "-std=c++11")
+endif()
+
+# Configure to run all the tests?
+if(${EXERCISM_RUN_ALL_TESTS})
+    add_definitions(-DEXERCISM_RUN_ALL_TESTS)
+endif()
+
+# Get a source filename from the exercise name by replacing -'s with _'s
+string(REPLACE "-" "_" file ${exercise})
+
+# Implementation could be only a header
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${file}.cpp)
+    set(exercise_cpp ${file}.cpp)
+else()
+    set(exercise_cpp "")
+endif()
+
+# Include a test helper header if it exists
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/require_equal_containers.h)
+    set(test_helper require_equal_containers.h)
+else()
+    set(test_helper "")
+endif()
+
+# Build executable from sources and headers
+add_executable(${exercise} ${file}_test.cpp ${test_helper} ${exercise_cpp} ${file}.h)
+
+# We need boost includes
+target_include_directories(${exercise} PRIVATE ${Boost_INCLUDE_DIRS})
+
+# We need boost libraries
+target_link_libraries(${exercise} ${Boost_LIBRARIES})
+
+# Tell MSVC not to warn us about unchecked iterators in debug builds
+if(${MSVC})
+    set_target_properties(${exercise} PROPERTIES
+        COMPILE_DEFINITIONS_DEBUG _SCL_SECURE_NO_WARNINGS)
+endif()
+
+# Run the tests on every build
+add_custom_command(TARGET ${exercise} POST_BUILD COMMAND ${exercise})

cpp/hexadecimal/README.md

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+# Hexadecimal
+
+Write a program that will convert a hexadecimal number, represented as a string (e.g. "10af8c"), to its decimal equivalent using first principles (i.e. no, you may not use built-in or external libraries to accomplish the conversion).
+
+On the web we use hexadecimal to represent colors, e.g. green: 008000,
+teal: 008080, navy: 000080).
+
+The program should handle invalid hexadecimal strings.
+
+## Getting Started
+
+Make sure you have read [the C++ page](http://exercism.io/languages/cpp) on
+exercism.io.  This covers the basic information on setting up the development
+environment expected by the exercises.
+
+## Passing the Tests
+
+Get the first test compiling, linking and passing by following the [three
+rules of test-driven development](http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd).
+Create just enough structure by declaring namespaces, functions, classes,
+etc., to satisfy any compiler errors and get the test to fail.  Then write
+just enough code to get the test to pass.  Once you've done that,
+uncomment the next test by moving the following line past the next test.
+
+```C++
+#if defined(EXERCISM_RUN_ALL_TESTS)
+```
+
+This may result in compile errors as new constructs may be invoked that
+you haven't yet declared or defined.  Again, fix the compile errors minimally
+to get a failing test, then change the code minimally to pass the test,
+refactor your implementation for readability and expressiveness and then
+go on to the next test.
+
+Try to use standard C++11 facilities in preference to writing your own
+low-level algorithms or facilities by hand.  [CppReference](http://en.cppreference.com/)
+is a wiki reference to the C++ language and standard library.  If you
+are new to C++, but have programmed in C, beware of
+[C traps and pitfalls](http://www.slideshare.net/LegalizeAdulthood/c-traps-and-pitfalls-for-c-programmers).
+
+## Source
+
+All of Computer Science [view source](http://www.wolframalpha.com/examples/NumberBases.html)

cpp/hexadecimal/hexadecimal.cpp

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+#include "hexadecimal.h"
+
+namespace hexadecimal {
+
+int convert(const std::string &input)
+{
+    int result = 0;
+
+    for (auto ch : input) {
+
+        ch = tolower(ch);
+
+        if (!isxdigit(ch))
+            return 0;
+
+        result *= 16;
+        result += ch <= '9' ? ch - '0'
+                            : ch - 'a' + 10;
+    }
+
+    return result;
+}
+
+}

cpp/hexadecimal/hexadecimal.h

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+#pragma once
+
+#define EXERCISM_RUN_ALL_TESTS
+
+#include <string>
+
+namespace hexadecimal {
+
+int convert(const std::string &input);
+
+}

cpp/hexadecimal/hexadecimal_test.cpp

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+#include "hexadecimal.h"
+#define BOOST_TEST_MAIN
+#include <boost/test/unit_test.hpp>
+
+BOOST_AUTO_TEST_CASE(hex_1_is_decimal_1)
+{
+    BOOST_REQUIRE_EQUAL(0x1, hexadecimal::convert("1"));
+}
+
+#if defined(EXERCISM_RUN_ALL_TESTS)
+BOOST_AUTO_TEST_CASE(hex_c_is_decimal_12)
+{
+    BOOST_REQUIRE_EQUAL(0xc, hexadecimal::convert("c"));
+}
+
+BOOST_AUTO_TEST_CASE(hex_10_is_decimal_16)
+{
+    BOOST_REQUIRE_EQUAL(0x10, hexadecimal::convert("10"));
+}
+
+BOOST_AUTO_TEST_CASE(hex_af_is_decimal_175)
+{
+    BOOST_REQUIRE_EQUAL(0xaf, hexadecimal::convert("af"));
+}
+
+BOOST_AUTO_TEST_CASE(hex_100_is_decimal_256)
+{
+    BOOST_REQUIRE_EQUAL(0x100, hexadecimal::convert("100"));
+}
+
+BOOST_AUTO_TEST_CASE(hex_19ace_is_decimal_105166)
+{
+    BOOST_REQUIRE_EQUAL(0x19ace, hexadecimal::convert("19ace"));
+}
+
+BOOST_AUTO_TEST_CASE(invalid_hex_is_decimal_0)
+{
+    BOOST_REQUIRE_EQUAL(0, hexadecimal::convert("carrot"));
+}
+
+BOOST_AUTO_TEST_CASE(black)
+{
+    BOOST_REQUIRE_EQUAL(0x000000, hexadecimal::convert("000000"));
+}
+
+BOOST_AUTO_TEST_CASE(white)
+{
+    BOOST_REQUIRE_EQUAL(0xffffff, hexadecimal::convert("ffffff"));
+}
+
+BOOST_AUTO_TEST_CASE(yellow)
+{
+    BOOST_REQUIRE_EQUAL(0xffff00, hexadecimal::convert("ffff00"));
+}
+#endif