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char a = "INCORRECT" Ī can only store 8 bytes of data, but we are trying to store 10 bytes ( ‘I’ ‘N’ ‘C’ ‘O’ ‘R’ ‘R’ ‘E’ ‘C’ ‘T’ ‘\0’ ). When you try to change the value like in the code, you will get a SEGFAULT. Once you go out of the if block, a is removed from memory and ptr now points to something which no longer exists. The variable a has a scope inside the if block. Now lets move on to the Dangling Pointers int *ptr With this, you will be trying to give the value a to *ptr, but as ptr is not initialized, it is pointing to some memory which you do not have access to. You are trying to change the value using *ptr, but ptr is a NULL pointer, and this might cause you a SEGFAULTĪn uninitialized pointer is a pointer which you have not referenced to anything char *ptr If you try something like int *ptr = NULL Now lets explain the dereferencing a NULL pointer These are the basic and most common causes of a Segfault. When you try to change the value of a variable marked as const using pointers.When dereferencing an uninitialized or dangling pointer.there are many cases, but the common ones are

If you try to access them, then it will lead to a SEGFAULT. The answer to the first is that you are not allowed to access memory which has not been allocated yet. But, you might ask which memory are we not allowed access to ? or when are we trying to access memory which does not belong to us ? A segmentation fault ( SEGFAULT ) occurs when you are trying to access memory which you should not be trying to access ( the memory which you have not allocated ).