std::string tempPath;
FileSel file;
{...}
tempPath = ~file[i]; // converts the Upp::String to const char*
//OR
tempPath = file[i].Begin(); // basically the same as above
//OR
tempPath = std::string(~file[i],file[i].GetLength()); // create a new std::string with the same content and length
//OR
tempPath = std::string(~file[i],file[i].GetLength()); // again, more verbose variation on the previous line