Use unused variable instead of hard-coded values in DateValue::copy

src/value.cpp

@@ -977,11 +977,10 @@ namespace Exiv2 {
         // sprintf wants to add the null terminator, so use oversized buffer
         char temp[9];
 
-        int wrote = sprintf(temp, "%04d%02d%02d",
-                            date_.year, date_.month, date_.day);
+        int wrote = sprintf(temp, "%04d%02d%02d", date_.year, date_.month, date_.day);
         assert(wrote == 8);
-        std::memcpy(buf, temp, 8);
-        return 8;
+        std::memcpy(buf, temp, wrote);
+        return wrote;
     }
 
     const DateValue::Date& DateValue::getDate() const