there are methods of sorting text files, but they are generally pretty complicated. If the file is small enough, just read all the strings into an in-memory array, sort the array, then rewrite them back to the file. If you are writing c++ program that is pretty easy -- read the strings into a std::vector<std::string> array, then use std::sort() to sort it.

Use a pretty recent compiler such as Dev-C++. The code you posted uses iostream.h which has been obsolete for several years, so I suspect you are using a pretty ancient compiler such as Turbo C++.