Problem in updating XML file

[Qt_Kid]

Dear Members,

I've created a sample application to save data in xml. Fist time it is saving data properly. But next time it is corrupting the file. I'm not able to find the problem. Here with I've attached the code. Can any body tell me what is problem in the code.

N.B. : the xml file will create in C drive with name VCS.xml

Thank you.