How to use the content of line Edit for 99 points and store in a file.txt

Hi All,
I have 3 line edits in DispForm namely X,Y,Z .and if i press a button in DispForm it will open new Form called DatumForm. In DatumForm i have 4 line edits namely datum number , xdat,ydat,zdat. now i will give 0-99 datum number and corresponding xdat,ydat,zdat values in line edits then i need to store these 100 values in a file.txt and when ever i press datum number 4 the corresponding xdat,ydat,zdat values should be read and these values are then displayed in X,Y,Z line edits of DispForm. Also i have attached the code and also ui design files.

So where is the problem? What did you already try?