Added factorial.

CMakeLists.txt

@@ -98,6 +98,7 @@ SET(COMPONENTS
     power
     division
     root
+    factorial
 )
 # NEW_COMPONENT: PATCH Do NOT remove the previous comment.
 

include/fn/basicArithm.hpp

@@ -212,6 +212,16 @@ namespace steppable::__internals::arithmetic
      */
     std::string rootIntPart(const std::string& _number, const std::string& base);
 
+    /**
+     * @brief Calculates the factorial of a number.
+     *
+     * @param _number The number to calculate the factorial of.
+     * @param steps The number of steps to calculate the factorial.
+     *
+     * @return The factorial of the number.
+     */
+    std::string factorial(const std::string& _number, int steps = 2);
+
     /**
      * @brief Executes a given predicate function a specified number of times.
      *

src/factorial/factorial.cpp

@@ -0,0 +1,112 @@
+/**************************************************************************************************
+ * Copyright (c) 2023-2024 NWSOFT                                                                 *
+ *                                                                                                *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy                   *
+ * of this software and associated documentation files (the "Software"), to deal                  *
+ * in the Software without restriction, including without limitation the rights                   *
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell                      *
+ * copies of the Software, and to permit persons to whom the Software is                          *
+ * furnished to do so, subject to the following conditions:                                       *
+ *                                                                                                *
+ * The above copyright notice and this permission notice shall be included in all                 *
+ * copies or substantial portions of the Software.                                                *
+ *                                                                                                *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR                     *
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,                       *
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE                    *
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER                         *
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,                  *
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE                  *
+ * SOFTWARE.                                                                                      *
+ **************************************************************************************************/
+
+/**
+ * @file add.cpp
+ * @brief This file contains the implementation of the add function, which add two number strings together.
+ *
+ * @author Andy Zhang
+ * @date 9th October 2023
+ */
+
+#include "argParse.hpp"
+#include "factorialReport.hpp"
+#include "fn/basicArithm.hpp"
+#include "output.hpp"
+#include "util.hpp"
+
+#include <algorithm>
+#include <iostream>
+#include <string_view>
+#include <vector>
+
+using namespace steppable::__internals::numUtils;
+using namespace steppable::__internals::utils;
+using namespace steppable::__internals::arithmetic;
+using namespace steppable::__internals::symbols;
+using namespace steppable::output;
+using namespace std::literals;
+
+namespace steppable::__internals::arithmetic
+{
+    std::string factorial(const std::string& _number, const int steps)
+    {
+        auto number = standardizeNumber(_number);
+        if (not isInteger(number))
+        {
+            // We cannot evaluate integrals yet, so this has to be returned.
+            // Correct implementation of the gamma function should be
+            //          / +inf
+            //          |      z-1  -s
+            //   G(z) = |     s    e   ds     ,where z is a non-zero decimal ............ (1)
+            //          |
+            //          / 0
+            // and factorial is defined as
+            //   n! = n * G(n)                ,where n is a non-zero decimal ............ (2)
+            error("factorial"s, "%s is not an integer."s, number.c_str());
+            return "0";
+        }
+        if (isZeroString(number))
+        {
+            if (steps == 2)
+                return "By definition, 0! = 1";
+            return "1"; // By definition, 0! = 1
+        }
+        // Negative numbers do not have a factorial.
+        if (number.front() == '-')
+        {
+            error("factorial"s, "%s is negative."s, number.c_str());
+            return "0";
+        }
+
+        // Calculate the factorial of the number
+        std::string result = "1";
+        loop(_number, [&](const std::string& i) { result = multiply(result, add(i, "1", 0), 0); });
+
+        return reportFactorial(_number, result, steps);
+    }
+} // namespace steppable::__internals::arithmetic
+
+#ifndef NO_MAIN
+int main(const int _argc, const char* _argv[])
+{
+    Utf8CodePage _;
+    ProgramArgs program(_argc, _argv);
+    program.addPosArg('a', "Number");
+    program.addKeywordArg("steps", 2, "Amount of steps while calculating the factorial. 0 = No steps, 2 = All steps.");
+    program.addSwitch("profile", false, "profiling the program");
+    program.parseArgs();
+
+    const int steps = program.getKeywordArgument("steps");
+    const bool profile = program.getSwitch("profile");
+    const auto& number = static_cast<std::string>(program.getPosArg(0));
+
+    if (profile)
+    {
+        TIC(Factorial)
+        std::cout << "Factorial :\n" << factorial(number, steps) << '\n';
+        TOC()
+    }
+    else
+        std::cout << factorial(number, steps) << '\n';
+}
+#endif

src/factorial/factorialReport.cpp

@@ -0,0 +1,48 @@
+/**************************************************************************************************
+ * Copyright (c) 2023-2024 NWSOFT                                                                 *
+ *                                                                                                *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy                   *
+ * of this software and associated documentation files (the "Software"), to deal                  *
+ * in the Software without restriction, including without limitation the rights                   *
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell                      *
+ * copies of the Software, and to permit persons to whom the Software is                          *
+ * furnished to do so, subject to the following conditions:                                       *
+ *                                                                                                *
+ * The above copyright notice and this permission notice shall be included in all                 *
+ * copies or substantial portions of the Software.                                                *
+ *                                                                                                *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR                     *
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,                       *
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE                    *
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER                         *
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,                  *
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE                  *
+ * SOFTWARE.                                                                                      *
+ **************************************************************************************************/
+
+#include "factorialReport.hpp"
+
+#include "fn/basicArithm.hpp"
+#include "symbols.hpp"
+
+#include <sstream>
+#include <string>
+
+using namespace steppable::__internals::arithmetic;
+using namespace steppable::__internals::symbols;
+
+std::string reportFactorial(const std::string& number, const std::string& result, int steps)
+{
+    if (steps == 0)
+        return result;
+
+    // In this case, steps == 2 is equivalent to steps == 1.
+    std::stringstream ss;
+    loop(number, [&](const auto& item) { ss << add(item, "1", 0) << " " << MULTIPLY << " "; });
+    auto out = ss.str();
+
+    out.erase(out.end() - 3, out.end()); // Remove the last " * "
+    out += " = " + result;
+
+    return out;
+}

src/factorial/factorialReport.hpp

@@ -0,0 +1,35 @@
+/**************************************************************************************************
+ * Copyright (c) 2023-2024 NWSOFT                                                                 *
+ *                                                                                                *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy                   *
+ * of this software and associated documentation files (the "Software"), to deal                  *
+ * in the Software without restriction, including without limitation the rights                   *
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell                      *
+ * copies of the Software, and to permit persons to whom the Software is                          *
+ * furnished to do so, subject to the following conditions:                                       *
+ *                                                                                                *
+ * The above copyright notice and this permission notice shall be included in all                 *
+ * copies or substantial portions of the Software.                                                *
+ *                                                                                                *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR                     *
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,                       *
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE                    *
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER                         *
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,                  *
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE                  *
+ * SOFTWARE.                                                                                      *
+ **************************************************************************************************/
+
+#pragma once
+
+#include <string>
+
+/**
+ * @brief Report the factorial calculation.
+ *
+ * @param number The number to calculate the factorial of.
+ * @param result The result of the factorial calculation.
+ * @param steps The number of steps taken to calculate the factorial.
+ * @return std::string The report of the factorial calculation.
+ */
+std::string reportFactorial(const std::string& number, const std::string& result, int steps);

tests/testFactorial.cpp

@@ -0,0 +1,38 @@
+/**************************************************************************************************
+ * Copyright (c) 2023-2024 NWSOFT                                                                 *
+ *                                                                                                *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy                   *
+ * of this software and associated documentation files (the "Software"), to deal                  *
+ * in the Software without restriction, including without limitation the rights                   *
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell                      *
+ * copies of the Software, and to permit persons to whom the Software is                          *
+ * furnished to do so, subject to the following conditions:                                       *
+ *                                                                                                *
+ * The above copyright notice and this permission notice shall be included in all                 *
+ * copies or substantial portions of the Software.                                                *
+ *                                                                                                *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR                     *
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,                       *
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE                    *
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER                         *
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,                  *
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE                  *
+ * SOFTWARE.                                                                                      *
+ **************************************************************************************************/
+
+#include "colors.hpp"
+#include "fn/basicArithm.hpp"
+#include "output.hpp"
+#include "testing.hpp"
+#include "util.hpp"
+
+#include <iomanip>
+#include <iostream>
+
+using namespace steppable::__internals::arithmetic;
+
+TEST_START()
+SECTION(Factorial)
+_.assertIsEqual(factorial("5", 0), "120");
+SECTION_END()
+TEST_END()