Pointer initialisation gives segmentation fault

Question

I wrote a C program as follows:

CASE 1

int *a; /* pointer variable declaration */

int b; /* actual variable declaration */

*a=11;

a=&b;/* st         


        

Answer 1

In the first case you have declared a pointer but you have not assigned the address to which it has to point hence the pointer would have contained an address that would have belonged to another process in the system (or it would have contained an junk value which is not an address at all or it would have contained an null which can't be an memory address)hence operating system sends an signal to prevent invalid memory operation and hence an segmentation fault occurs.

In the second case you are assigning the address of the variable which has to be updated to the pointer and storing the value which is the correct way of doing and hence there's no segmentation fault.