Advance-C/C2/Union-and-Typedef/Gujarati

Time	Narration
00:01	Welcome to the Spoken Tutorial on Typedef and Union in C.
00:07	In this tutorial, we will learn about typedef keyword union keyword with the help of some examples.
00:17	For this tutorial I am using Ubuntu Operating System version 11.10. gcc compiler version 4.6.1 on Ubuntu
00:29	To follow this tutorial, you should be familiar with C tutorials.
00:36	If not, for relevant tutorials please visit our website which is as shown.
00:43	I will start with an introduction to typedef keyword.
00:49	Typedef keyword is used to give symbolic name to an existing type or user-defined datatypes.
00:58	It is a way to define alias to the commands.
01:03	It helps to provide clarity to the code.
01:07	It makes the code easier to understand and change.
01:12	Syntax: typedef existing_name alias_name. Example: typedef unsigned int uint;
01:24	Let us go through an example code.
01:28	Note that our filename is pallindrome.c
01:34	In this program, we will check whether the given number is a pallindrome or not.
01:41	We have given alias name as uint to the unsigned int datatype using typedef keyword.
01:52	Here we are using uint to declare the variables.
01:59	This is the logic for pallindrome.
02:03	Now let us execute the program.
02:06	Open the terminal by pressing Ctrl+Alt+T keys simultaneously on your keyboard.
02:16	Type gcc space pallindrome dot c space hyphen o space pallindrome. Press Enter.
02:29	Type: dot slash pallindrome
02:34	We see: Enter any three digit number
02:38	I will enter 121
02:42	The output is: Given number is a palindrome number
02:47	Now we will learn about union datatype.
02:52	Union is a collection of different datatypes grouped together.
02:57	Union allocates one common storage space for all its members.
03:03	We can access only one member of union at a time.
03:08	Syntax1: union union_name within curly brackets members; after curly brackets union_variable and a semi-colon.
03:21	We also have an alternate syntax. Syntax 2: union union_name within curly brackets members; after curly brackets semi-colon union union_name union_variable;
03:39	Let us see an example.
03:41	I have a code file; let us go through it.
03:47	Note that our filename is union dot c
03:52	We have declared union named student.
03:56	Here we have three variables english, maths and science.
04:02	In main function, we have declared a union variable as stud.
04:09	Here we can access the union members using a union variable: stud dot english stud dot maths stud dot science
04:21	Then we calculate the total marks and display it.
04:26	Let us execute. On the terminal, type, gcc space union dot c space hyphen o space union Type dot slash union
04:44	The output is displayed as: Total is 228
04:50	Let us see the difference between structure and union.
04:55	Union allocates a common storage space for all its members.
05:01	Structure allocates separate storage space for all its members.
05:07	Union occupies lower memory space.
05:11	Structure occupies higher memory space.
05:14	Example for union: union student{int marks;char name[6];double average;};
05:27	Memory allocation for union variable will be 8 bytes. As double datatype will occupy the maximum memory space.
05:39	Exampls for structure: struct student{int mark;char name[6];double average;};
05:48	Memory allocation for structure variable will be: 2bytes+6bytes+8bytes =16bytes.
06:00	This brings us to the end of this tutorial.
06:04	Let us summarize.
06:06	In this tutorial we learnt, typedef union Difference between union and structure.
06:14	As an assignment,
06:17	Write a program to display records of an employee.
06:21	Like name, address, salary.
06:25	Define a union named employee.
06:29	Give an alias name as emp using typedef.
06:35	Watch the video available at the link shown below
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07:22	This is Ashwini Patil from IIT Bombay. Thank you for joining.

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Jyotisolanki, PoojaMoolya