What is segmentation fault??

Answer 1

A segmentation fault (aka segfault) is a common condition that causes programs to crash; they are often associated with a file named core . Segfaults are caused by a program trying to read or write an illegal memory location.

Answer 2

You are using memory which you cannot have access to. For example if you have array of size 5 and using array[5], array[6], array[7] etc..