either decide whether you are going to use a class and let selection sort sort the held array pointed at by the int* member, in which case you will need a different constructor than a default one and you will also need to think about copying operations as the int* will point to dynamically allocated memory. Or alternatively keep everything as it is but instead use free functions wrapped inside a namespace. There is no point in using a class if theres no data held. Classes consisting of static functions and no data are pretty pointless most of the time.