C: roman numerals

c/roman-numerals/GNUmakefile

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+# The original 'makefile' has a flaw:
+# 1) it overrides CFLAGS
+# 2) it does not pass extra "FLAGS" to $(CC) that could come from environment
+#
+# It means :
+# - we need to edit 'makefile' for different builds (DEBUG, etc...), which is
+#   not practical at all.
+# - Also, it does not allow to run all tests without editing the test source
+#   code.
+#
+# To use this makefile (GNU make only):
+#   "make": build with all predefined tests (without editing test source code)
+#   "make debugall": build with all predefined tests and debug code
+#   "make mem": perform memcheck with all tests enabled
+#   "make unit": build standalone (unit) test
+#   "make debug": build standalone test with debugging code
+#
+# Original 'makefile' targets can be used (test, memcheck, clean, ...)
+
+.PHONY: default all mem unit debug std debugtest
+
+default: all
+
+# default is to build with all predefined tests
+BUILD := teststall
+
+include makefile
+
+all: CFLAGS+=-DTESTALL
+all: clean test
+
+debugall: CFLAGS+=-DDEBUG
+debugall: all
+
+debugtest: CFLAGS+=-DDEBUG
+debugtest: test
+
+mem: CFLAGS+=-DTESTALL
+mem: clean memcheck
+
+unit: CFLAGS+=-DUNIT_TEST
+unit: clean std
+
+debug: CFLAGS+=-DUNIT_TEST -DDEBUG
+debug: clean std
+
+debugtest: CFLAGS+=-DDEBUG
+debugtest: test
+
+std: src/*.c src/*.h
+	$(CC) $(CFLAGS) src/*.c -o test.out

c/roman-numerals/README.md

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+# Roman Numerals
+
+Write a function to convert from normal numbers to Roman Numerals.
+
+The Romans were a clever bunch. They conquered most of Europe and ruled
+it for hundreds of years. They invented concrete and straight roads and
+even bikinis. One thing they never discovered though was the number
+zero. This made writing and dating extensive histories of their exploits
+slightly more challenging, but the system of numbers they came up with
+is still in use today. For example the BBC uses Roman numerals to date
+their programmes.
+
+The Romans wrote numbers using letters - I, V, X, L, C, D, M. (notice
+these letters have lots of straight lines and are hence easy to hack
+into stone tablets).
+
+```text
+ 1  => I
+10  => X
+ 7  => VII
+```
+
+There is no need to be able to convert numbers larger than about 3000.
+(The Romans themselves didn't tend to go any higher)
+
+Wikipedia says: Modern Roman numerals ... are written by expressing each
+digit separately starting with the left most digit and skipping any
+digit with a value of zero.
+
+To see this in practice, consider the example of 1990.
+
+In Roman numerals 1990 is MCMXC:
+
+1000=M
+900=CM
+90=XC
+
+2008 is written as MMVIII:
+
+2000=MM
+8=VIII
+
+See also: http://www.novaroma.org/via_romana/numbers.html
+
+## Getting Started
+
+Make sure you have read the "Guides" section of the
+[C track][c-track] on the Exercism site. 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][3-tdd-rules].
+
+The included makefile can be used to create and run the tests using the `test`
+task.
+
+    make test
+
+Create just the functions you need 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, move onto the next test.
+
+As you progress through the tests, take the time to refactor your
+implementation for readability and expressiveness and then go on to the next
+test.
+
+Try to use standard C99 facilities in preference to writing your own
+low-level algorithms or facilities by hand.
+
+## Source
+
+The Roman Numeral Kata [http://codingdojo.org/cgi-bin/index.pl?KataRomanNumerals](http://codingdojo.org/cgi-bin/index.pl?KataRomanNumerals)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
+[c-track]: https://exercism.io/my/tracks/c
+[3-tdd-rules]: http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd

c/roman-numerals/makefile

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+### If you wish to use extra libraries (math.h for instance),
+### add their flags here (-lm in our case) in the "LIBS" variable.
+
+LIBS = -lm
+
+###
+CFLAGS  = -std=c99
+CFLAGS += -g
+CFLAGS += -Wall
+CFLAGS += -Wextra
+CFLAGS += -pedantic
+CFLAGS += -Werror
+CFLAGS += -Wmissing-declarations
+CFLAGS += -DUNITY_SUPPORT_64
+
+ASANFLAGS  = -fsanitize=address
+ASANFLAGS += -fno-common
+ASANFLAGS += -fno-omit-frame-pointer
+
+.PHONY: test
+test: tests.out
+	@./tests.out
+
+.PHONY: memcheck
+memcheck: test/*.c src/*.c src/*.h
+	@echo Compiling $@
+	@$(CC) $(ASANFLAGS) $(CFLAGS) src/*.c test/vendor/unity.c test/*.c -o memcheck.out $(LIBS)
+	@./memcheck.out
+	@echo "Memory check passed"
+
+.PHONY: clean
+clean:
+	rm -rf *.o *.out *.out.dSYM
+
+tests.out: test/*.c src/*.c src/*.h
+	@echo Compiling $@
+	@$(CC) $(CFLAGS) src/*.c test/vendor/unity.c test/*.c -o tests.out $(LIBS)

c/roman-numerals/src/roman_numerals.c

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+#include "roman_numerals.h"
+#include <stdio.h>
+#include <string.h>
+#include <malloc.h>
+
+/* V1: initial working version
+ * V2 & V3: code simplification
+ */
+
+static struct conv_s {
+    unsigned char r;
+    unsigned d;
+} conv[] = {
+    { 'M', 1000 },
+    { 'D',  500 },
+    { 'C',  100 },
+    { 'L',   50 },
+    { 'X',   10 },
+    { 'V',    5 },
+    { 'I',    1 }
+};
+
+/* rules could differ (like IIII/VIIII instead of IV/IX), so it is better not
+ * to harcode values like 4, 9, 40, 90 etc...
+ * Example: the Colosseum gate 44 was written XLIIII, and not XLIV.
+ * we can therefore add a parameter in function below, and add a rule in
+ * the code to easily return a different notation.
+ */
+char *to_roman_numeral(unsigned int n /*, int notation */ )
+{
+    unsigned cur=0, mult, pos=0, i;
+    char res[64]={0}, *to;
+
+    /* max number = 3999 = MMMCMXCIX */
+    if (n >= 4000)                                /* could be different if we */
+        return NULL;                              /* accept the 5000 sign */
+
+    while (n) {
+        /* we could : switch (notation) {
+         *              case ROMAN_RULE:
+         */
+        if ((mult=n/conv[cur].d)) {               /* >= current multiplier */
+            if (mult%5==4) {                      /* 4 & 9 */
+                res[pos++]=conv[cur].r;
+                res[pos++]=conv[cur-mult/4].r;    /* 4/4=1, 9/4=2 */
+            } else {                              /* 1-3 & 5-8 */
+                if (mult >= 5)
+                    res[pos++]=conv[cur-1].r;
+                for (i=mult%5; i>0; --i)
+                    res[pos++]=conv[cur].r;
+            }
+        }
+        n-=mult*conv[cur].d;
+        cur+=2;
+    }
+    if ((to=malloc(pos+1)))
+        memcpy(to, res, pos+1);
+    return to;
+}
+
+
+/* See GNUmakefile below for explanation
+ * https://github.com/braoult/exercism/blob/master/c/templates/GNUmakefile
+ */
+#ifdef UNIT_TEST
+#include <stdlib.h>
+int main(int ac, char **av)
+{
+    int arg=1;
+    unsigned i;
+
+    for (; arg<ac; ++arg) {
+        i=atoi(av[arg]);
+        printf("roman(%d)=%s\n", i, to_roman_numeral(i));
+    }
+}
+#endif

c/roman-numerals/src/roman_numerals.h

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+#ifndef ROMAN_NUMERALS_H
+#define ROMAN_NUMERALS_H
+
+#define ROMAN_RULE 0
+
+char *to_roman_numeral(unsigned int number);
+
+/* See GNUmakefile below for explanation
+ * https://github.com/braoult/exercism/blob/master/c/templates/GNUmakefile
+ */
+#if defined UNIT_TEST || defined DEBUG
+#include <stdio.h>
+#include <stdlib.h>
+#endif
+#ifdef  TESTALL
+#undef  TEST_IGNORE
+#define TEST_IGNORE() {}
+#endif
+
+#endif