is_nan and is_infinity macros

cJSON.c

@@ -471,6 +471,9 @@ static void update_offset(printbuffer * const buffer)
     buffer->offset += strlen((const char*)buffer_pointer);
 }
 
+#define is_nan(number) (number != number)
+#define is_infinity(number) (!is_nan(number) && (number * 0) != 0)
+
 /* Render the number nicely from the given item into a string. */
 static cJSON_bool print_number(const cJSON * const item, printbuffer * const output_buffer)
 {
@@ -487,8 +490,7 @@ static cJSON_bool print_number(const cJSON * const item, printbuffer * const out
         return false;
     }
 
-    /* This checks for NaN and Infinity */
-    if ((d * 0) != 0)
+    if (is_nan(d) || is_infinity(d))
     {
         length = sprintf((char*)number_buffer, "null");
     }