Difference between revisions of "Advance-C/C2/Union-and-Typedef/English-timed"

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| I will start with an introduction to '''typedef keyword.'''
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| We have given '''alias '''name as 'uint' to the''' unsigned int datatype '''using''' typedef''' keyword.
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| The output is: '''"Given number is a palindrome number".'''
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| Now we will learn about '''union datatype.'''
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| Now we will learn about '''union''' datatype.
  
 
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| '''Union''' is a collection of different datatypes grouped together.
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| '''union''' is a collection of different data types grouped together.
  
 
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| '''Union '''allocates one common storage space for all its members.
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| '''union '''allocates one common storage-space for all its members.
  
 
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| We can access only one member of union at a time.  
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| Note that our filename is "union dot c".
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| Note that our file-name is "union dot c".
  
 
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| We have declared '''union''' named '''student.'''
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| The output is displayed as: '''"Total is 228"'''.
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Revision as of 18:09, 9 December 2015

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 data types 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 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 file-name 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.
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:

http://spoken-tutorial.org\NMEICT-Intro

07:22 This is Ashwini Patil from IIT Bombay.

Thank you for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14

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