What is the Cause of ??

What is the cause of buffer overrun or buffer overflow?

Sometimes it's memory leeks, use debug mode :)

when i dedug theres no result of problem.

It happens when your allocated memory (buffer) takes more than defined in the allocation (it overflows).

so is not the source problem?

i mean code problem?

It is. ;)

how do i find causing of buffer overflow

Well, I never had buffer overflows, but I suggest to always run in debug mode until your issue is solved. Next thing is to set breakpoints and control your buffer.

Btw, did you ever tried run in debug mode (-> Run -> New Debug Instance)
If yes, what does your compiler show when your binary crashes?