My char pointer points to invalid value after being cast from int*

Question

I am learning C programming language, I have just started learning arrays with pointers. I have problem in this question, I hope the that output must be

Answer 1

Assumed a little endian architecture where an int is 32 bits (4 bytes), the individual bytes of int arr[] look like this (least significant byte at the lower address. All values in hex):

|01 00 00 00|02 00 00 00|03 00 00 00|04 00 00 00|05 00 00 00

char *ptr = (char *) arr;

Now, ptr points to the first byte - since you have casted to char*, it is treated as char array onwards:

|1|0|0|0|2|0|0|0|3|0|0|0|4|0|0|0|5|0|0|0
 ^
 +-- ptr

Then, *(ptr+4) accesses the fifth element of the char array and returns the corresponding char value:

|1|0|0|0|2|0|0|0|3|0|0|0|4|0|0|0|5|0|0|0
         ^
         +-- *(ptr + 4) = 2

Hence, printf() prints 2.

On a Big Endian system, the order of the bytes within each int is reversed, resulting in

|0|0|0|1|0|0|0|2|0|0|0|3|0|0|0|4|0|0|0|5
         ^
         +-- *(ptr + 4) = 0