add TO_UNITS_ON_THE_END and FROM_UNITS_ON_THE_END

 * add reverse_string()
 * number variable instead of number_first/number_last
 * add flags TO_UNITS_ON_THE_END and FROM_UNITS_ON_THE_END

Signed-off-by: Daniel Santos <dacs.git@brilhante.top>

1 files changed, 49 insertions, 6 deletions

diff --git a/numericx.c b/numericx.c
index 87cde70..2a611d8 100644
--- a/numericx.c
+++ b/numericx.c
@@ -10,6 +10,18 @@
 #define DEBUG false
 #endif
 
+#ifdef TO_UNITS_ON_THE_END
+#define TO_UNITS_ON_THE_END true
+#else
+#define TO_UNITS_ON_THE_END false
+#endif
+
+#ifdef FROM_UNITS_ON_THE_END
+#define FROM_UNITS_ON_THE_END true
+#else
+#define FROM_UNITS_ON_THE_END false
+#endif
+
 typedef struct NumeralPtr
 {
 	char const* symbol;
@@ -83,15 +95,43 @@ is_the_same(numeral_ptr* numeral, char* number_arg)
 void
 print_numeral(numeral_ptr* numeral)
 {
-	while( !(numeral == NULL) )
+	if( TO_UNITS_ON_THE_END )
 	{
-		printf("%c", *(numeral->symbol));
-		numeral = numeral->next;
+		while( !(numeral->next == NULL) )
+			numeral = numeral->next;
+
+		while( !(numeral == NULL) )
+		{
+			printf("%c", *(numeral->symbol));
+			numeral = numeral->previous;
+		}
+	}
+	else
+	{
+		while( !(numeral == NULL) )
+		{
+			printf("%c", *(numeral->symbol));
+			numeral = numeral->next;
+		}
 	}
 
 	printf("\n");
 }
 
+void
+reverse_string(char* string)
+{
+	char tmp;
+	char* string_end = string + strlen(string);
+
+	while ( --string_end > string )
+	{
+		tmp = *string;
+		*string++ = *string_end;
+		*string_end = tmp;
+	}
+}
+
 int
 main(int argc, char* argv[])
 {
@@ -121,15 +161,17 @@ main(int argc, char* argv[])
 	char* to_first = to;
 	char* to_last = to + (strlen(to) - 1);
 
-	char* number_first = number;
-	char* number_last = number + (strlen(number) - 1);
+	if( FROM_UNITS_ON_THE_END )
+	{
+		reverse_string(number);
+	}
 
 	/* initializing counting and result */
 	numeral_ptr* counting = new_digit(NULL, from_first);
 	numeral_ptr* result = new_digit(NULL, to_first);
 
 	/* increments until it finishes */
-	while( !is_the_same(counting, number_first) )
+	while( !is_the_same(counting, number) )
 	{
 		if(DEBUG)
 		{
@@ -152,6 +194,7 @@ main(int argc, char* argv[])
 		print_numeral(counting);
 		printf("result: ");
 	}
+
 	print_numeral(result);
 
 	return EXIT_SUCCESS;