feat(solutions): add look-and-say-sequence-conway/c/function

challenges/look-and-say-sequence-conway/solutions/c/function/character.h

@@ -0,0 +1,22 @@
+#ifndef __CHARACTER__
+#define __CHARACTER__
+
+/**
+ * @brief Append a character to a string, assuming string points to an array
+ * with enough space.
+ *
+ * @param string
+ * @param character
+ */
+void character_append(char* string, char character);
+
+/**
+ * @brief Append many characters to a string, assuming string points to an array
+ * with enough space.
+ *
+ * @param string
+ * @param characters
+ */
+void character_append_many(char* string, char* characters);
+
+#endif