Typecasting exercise
=========================

.. tab-set::

    .. tab-item:: Question 1 : What is the output of below code and why ?

	.. code-block:: c
		:linenos:

		#include <stdio.h>

		int main(void)
		{
			char arr[] = { 0x11, 0x22, 0x33, 0x44 };

			unsigned int *ptr;

			ptr = (unsigned int *)arr;

			printf("*ptr = %x\n", *ptr);

			return 0;
		}

	.. dropdown:: See Answer

		.. code-block:: c
			:linenos:

			*ptr = 44332211

		* Note that memory is organised as below in array and integer

			* 0x11 is byte 0

			* 0x22 is byte 1

			* 0x33 is byte 2

			* 0x44 is byte 3

		* printf prints bytes from right to left

.. tab-set::

    .. tab-item:: Question 2 : What is the output of below code and why ?

	.. code-block:: c
		:linenos:

		#include <stdio.h>

		int main(void)
		{
			char arr[] = { 0x44, 0x33, 0x22, 0x11 };

			unsigned int *ptr;

			ptr = (unsigned int *)arr;

			printf("*ptr = %x\n", *ptr);

			return 0;
		}

	.. dropdown:: See Answer

		.. code-block:: c
			:linenos:

			*ptr = 11223344

		* Note that memory is organised as below in array and integer

			* 0x44 is byte 0

			* 0x33 is byte 1

			* 0x22 is byte 2

			* 0x11 is byte 3

		* printf prints bytes from right to left
.. tab-set::

    .. tab-item:: Question 3 : What is the output of below code and why ?

	.. code-block:: c
		:linenos:


		#include <stdio.h>

		int main(void)
		{
		        unsigned int a = 0x11223344;

		        unsigned char *ptr;

		        ptr = (unsigned char *)&a;

		        printf("ptr[0] = %x\n", ptr[0]);
		        printf("ptr[1] = %x\n", ptr[1]);
		        printf("ptr[2] = %x\n", ptr[2]);
		        printf("ptr[3] = %x\n", ptr[3]);

		        return 0;
		}

	.. dropdown:: See Answer

		.. code-block:: c
			:linenos:

			ptr[0] = 44
			ptr[1] = 33
			ptr[2] = 22
			ptr[3] = 11

		* Note that memory is organised as below in integer

			* 0x44 is byte 0

			* 0x33 is byte 1

			* 0x22 is byte 2

			* 0x11 is byte 3

		* printf prints bytes from right to left
.. tab-set::

    .. tab-item:: Question 4 : What is the output of below code and why ?

	.. code-block:: c
		:linenos:

		#include <stdio.h>

		int main(void)
		{
		        unsigned int a = 0x44332211;

		        unsigned char *ptr;

		        ptr = (unsigned char *)&a;

		        printf("ptr[0] = %x\n", ptr[0]);
		        printf("ptr[1] = %x\n", ptr[1]);
		        printf("ptr[2] = %x\n", ptr[2]);
		        printf("ptr[3] = %x\n", ptr[3]);

		        return 0;
		}

	.. dropdown:: See Answer

		.. code-block:: c
			:linenos:

			ptr[0] = 11
			ptr[1] = 22
			ptr[2] = 33
			ptr[3] = 44

		* Note that memory is organised as below in integer

			* 0x11 is byte 0

			* 0x22 is byte 1

			* 0x33 is byte 2

			* 0x44 is byte 3

		* printf prints bytes from right to left

.. tab-set::

    .. tab-item:: Question 5 : What is the output of below code and why ?

	.. code-block:: c
		:linenos:

		#include <stdio.h>

		unsigned char buffer[] = {0x11, 0x22, 0x45, 0x67, 0xc0, 0xb5, 0xd7, 0x0b, 0xac, 0x5b};

		struct hdr {
		        unsigned short int fc;
		        unsigned short int duration;
		        unsigned char ra_addr[6];
		};

		int main(void)
		{
		        struct hdr *phdr;

		        phdr = (struct hdr *) buffer;

		        printf("phdr->fc = %x\n", phdr->fc);
		        printf("phdr->duration = %x\n", phdr->duration);

		        printf("phdr->ra_addr[0] = %x\n", phdr->ra_addr[0]);
		        printf("phdr->ra_addr[1] = %x\n", phdr->ra_addr[1]);
		        printf("phdr->ra_addr[2] = %x\n", phdr->ra_addr[2]);
		        printf("phdr->ra_addr[3] = %x\n", phdr->ra_addr[3]);
		        printf("phdr->ra_addr[4] = %x\n", phdr->ra_addr[4]);
		        printf("phdr->ra_addr[5] = %x\n", phdr->ra_addr[5]);

		        return 0;
		}

	.. dropdown:: See Answer

		.. code-block:: c
			:linenos:

			phdr->fc = 2211
			phdr->duration = 6745
			phdr->ra_addr[0] = c0
			phdr->ra_addr[1] = b5
			phdr->ra_addr[2] = d7
			phdr->ra_addr[3] = b
			phdr->ra_addr[4] = ac
			phdr->ra_addr[5] = 5b

.. card:: See Also

        * Current Module

                * :doc:`typecasting_n_ptr`

        * Previous Module

                * :doc:`../malloc_ptr/malloc_ptr`

        * Next Module

                * :doc:`../funcs_n_ptrs/funcs_n_ptrs`

        * Other Modules

                * :doc:`../variable_and_ptr/variable_and_ptr`
                * :doc:`../array_n_ptrs/array_n_ptrs`
                * :doc:`../memcpy_ptr/memcpy_ptr`
                * :doc:`../const_ptr/const_ptr`
                * :doc:`../void_ptr/void_ptr`
                * :doc:`../array_of_ptr/array_of_ptr`
                * :doc:`../ptr_to_array/ptr_to_array`
                * :doc:`../function_ptr/function_ptr`
                * :doc:`../pre_incr_ptr/pre_incr_ptr`
                * :doc:`../post_incr_ptr/post_incr_ptr`
                * :doc:`../pre_decr_ptr/pre_decr_ptr`
                * :doc:`../post_decr_ptr/post_decr_ptr`