Advance-C/C2/Union-and-Typedef/English-timed
From Script | Spoken-Tutorial
| 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 palindrome 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 palindrome. |
| 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_variableand a semicolon. |
| 03:21 | We also have an alternate syntax.
Syntax 2: union union_name within curly brackets members; after curly brackets semicolon 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 | Example 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 and 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. |
| 06:39 | It summarizes the Spoken Tutorial project. |
| 06:42 | If you do not have good bandwidth, you can download and watch it. |
| 06:47 | The Spoken Tutorial project team: * Conducts workshops using spoken tutorials. |
| 06:53 | Gives certificates to those who pass an online test. For more details, please write to contact@spoken-tutorial.org |
| 07:04 | Spoken Tutorial project is a part of the Talk to a Teacher project. |
| 07:08 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 07:16 | More information on this mission is available at the link shown below:http://spoken-tutorial.org\NMEICT-Intro |
| 07:22 | This is Ashwini Patil from IIT Bombay, signing off.Thank you for joining. |
