tasks a-s

Task/Roman-numerals-Encode/C/roman-numerals-encode-1.c

@@ -0,0 +1,59 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+/*
+ * Writes the Roman numeral representing n into the buffer s.
+ * Handles up to n = 3999.
+ * Since C doesn't have exceptions, n = 0 causes the whole program to exit
+ * unsuccessfully.
+ * s should be have room for at least 16 characters, including the trailing
+ * null.
+ */
+void roman(char *s, unsigned int n)
+{
+ if (n == 0)
+ {
+  fputs(stderr, "Roman numeral for zero requested.");
+  exit(EXIT_FAILURE);
+ }
+
+  #define digit(loop, num, c) \
+      loop (n >= num)         \
+         {*(s++) = c;         \
+          n -= num;}
+  #define digits(loop, num, c1, c2) \
+      loop (n >= num)               \
+         {*(s++) = c1;              \
+          *(s++) = c2;              \
+          n -= num;}
+
+  digit  ( while, 1000, 'M'      )
+  digits ( if,     900, 'C', 'M' )
+  digit  ( if,     500, 'D'      )
+  digits ( if,     400, 'C', 'D' )
+  digit  ( while,  100, 'C'      )
+  digits ( if,      90, 'X', 'C' )
+  digit  ( if,      50, 'L'      )
+  digits ( if,      40, 'X', 'L' )
+  digit  ( while,   10, 'X'      )
+  digits ( if,       9, 'I', 'X' )
+  digit  ( if,       5, 'V'      )
+  digits ( if,       4, 'I', 'V' )
+  digit  ( while,    1, 'I'      )
+
+  #undef digit
+  #undef digits
+
+  *s = 0;}
+
+int main(void)
+{
+ char buffer[16];
+ unsigned int i;
+ for (i = 1 ; i < 4000 ; ++i)
+ {
+  roman(buffer, i);
+  printf("%4u: %s\n", i, buffer);
+ }
+ return EXIT_SUCCESS;
+}

Task/Roman-numerals-Encode/C/roman-numerals-encode-2.c

@@ -0,0 +1,38 @@
+char *ToRoman(int num, char *buf, int buflen)
+{
+   static const char romanDgts[] = "ivxlcdmVXLCDM_";
+   char *roman = buf + buflen;
+   int  rdix, r, v;
+   *--roman = '\0';        /* null terminate return string */
+   if (num >= 4000000) {
+      printf("Number Too Big.\n");
+      return NULL;
+      }
+   for (rdix = 0; rdix < strlen(romanDgts); rdix += 2) {
+      if (num == 0) break;
+      v = (num % 10) / 5;
+      r = num % 5;
+      num = num / 10;
+      if (r == 4) {
+         if (roman < buf+2) {
+            printf("Buffer too small.");
+            return NULL;
+            }
+         *--roman = romanDgts[rdix+1+v];
+         *--roman = romanDgts[rdix];
+         }
+      else {
+         if (roman < buf+r+v) {
+            printf("Buffer too small.");
+            return NULL;
+            }
+         while(r-- > 0) {
+            *--roman = romanDgts[rdix];
+            }
+         if (v==1) {
+            *--roman = romanDgts[rdix+1];
+            }
+         }
+      }
+   return roman;
+}

Task/Roman-numerals-Encode/C/roman-numerals-encode-3.c

@@ -0,0 +1,40 @@
+#include <stdio.h>
+
+int to_roman(char *out, int n)
+{
+        int len = 0;
+        if (n <= 0) return 0; /* error indication */
+#       define RPUT(c) if (out) out[len] = c; len++
+        while(n>= 1000) { n -= 1000;RPUT('M'); };
+
+        if (n >= 900)   { n -= 900; RPUT('C'); RPUT('M'); };
+        if (n >= 500)   { n -= 500; RPUT('D'); };
+        if (n >= 400)   { n -= 400; RPUT('C'); RPUT('D'); };
+        while (n >= 100){ n -= 100; RPUT('C'); };
+
+        if (n >= 90)    { n -= 90;  RPUT('X'); RPUT('C'); };
+        if (n >= 50)    { n -= 50;  RPUT('L'); };
+        if (n >= 40)    { n -= 40;  RPUT('X'); RPUT('L'); };
+        while (n >= 10) { n -= 10;  RPUT('X'); };
+
+        if (n >= 9)     { n -= 9;   RPUT('I'); RPUT('X'); };
+        if (n >= 5)     { n -= 5;   RPUT('V'); };
+        if (n >= 4)     { n -= 4;   RPUT('I'); RPUT('V'); };
+        while (n)       { n--; RPUT('I'); };
+        RPUT('\0');
+#       undef RPUT
+
+        return len;
+}
+
+int main()
+{
+        char buf[16];
+        int d = to_roman(buf, 1666);
+        printf("roman for 1666 is %d bytes: %s\n", d, buf);
+
+        d = 68999123;
+        printf("%d would have required %d bytes\n", d, to_roman(0, d));
+
+        return 0;
+}