ext/calc/calc.c in calc-nik-0.0.4 vs ext/calc/calc.c in calc-nik-0.0.5

@@ -1,19 +1,117 @@
 #include <ruby.h>
 
-/* our new native method; it just returns
- * the string "bonjour!" */
-static VALUE calc_bonjour(VALUE self) {
-  return rb_str_new2("bonjour!");
+int is_palindrome(char*);
+void copy_string(char*, char*);
+void reverse_string(char*);
+int string_length(char*);
+int compare_string(char*, char*);
+ 
+static VALUE palindrom(VALUE self, VALUE string_raw)
+{
+   char *string = StringValuePtr(string_raw);
+   int result;
+ 
+   result = is_palindrome(string);
+ 
+   if ( result == 1 )
+      return Qtrue;
+   else
+      return Qfalse;
 }
+ 
+int is_palindrome(char *string)
+{
+   int check, length;
+   char *reverse;
+ 
+   length = string_length(string);    
+   reverse = (char*)malloc(length+1);    
+ 
+   copy_string(reverse, string);
+   reverse_string(reverse);
+ 
+   check = compare_string(string, reverse);
+ 
+   free(reverse);
+ 
+   if ( check == 0 )
+      return 1;
+   else
+      return 0;
+}
+ 
+int string_length(char *string)
+{
+   int length = 0;  
+ 
+   while(*string)
+   {
+      length++;
+      string++;
+   }
+ 
+   return length;
+}
+ 
+void copy_string(char *target, char *source)
+{
+   while(*source)
+   {
+      *target = *source;
+      source++;
+      target++;
+   }
+   *target = '\0';
+}
+ 
+void reverse_string(char *string) 
+{
+   int length, c;
+   char *begin, *end, temp;
+ 
+   length = string_length(string);
+ 
+   begin = string;
+   end = string;
+ 
+   for ( c = 0 ; c < ( length - 1 ) ; c++ )
+       end++;
+ 
+   for ( c = 0 ; c < length/2 ; c++ ) 
+   {        
+      temp = *end;
+      *end = *begin;
+      *begin = temp;
+ 
+      begin++;
+      end--;
+   }
+}
+ 
+int compare_string(char *first, char *second)
+{
+   while(*first==*second)
+   {
+      if ( *first == '\0' || *second == '\0' )
+         break;
+ 
+      first++;
+      second++;
+   }
+   if( *first == '\0' && *second == '\0' )
+      return 0;
+   else
+      return -1;
+}
 
 /* ruby calls this to load the extension */
 void Init_calc(void) {
   /* assume we haven't yet defined Hola */
   VALUE klass = rb_define_class("Calc_c",
       rb_cObject);
 
-  /* the hola_bonjour function can be called
-   * from ruby as "Hola.bonjour" */
+  /* the palindrom function can be called
+   * from ruby as "Calc_c.palindrom?" */
   rb_define_singleton_method(klass,
-      "bonjour", calc_bonjour, 0);
+      "palindrom?", palindrom, 1);
 }
\ No newline at end of file