View source for C-and-C++/C4/Understanding-Pointers/English-timed

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|Time
|Narration

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| 00:01
|Welcome to the spoken tutorial on '''Pointers in C and C++ '''.

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| 00:06
|In this tutorial we will learn:   

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| 00:08
|* Pointers 

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| 00:10
|* To create Pointers 

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| 00:12
|* And operations on Pointers. 

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| 00:14
| We will do this with the help of an example.

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| 00:18
|To record this tutorial, I am using '''Ubuntu operating system''' version 11.10,

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| 00:25
| '''gcc and g++ compiler''' version 4.6.1 on Ubuntu.

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| 00:31
|Let us start with an introduction to pointers.

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|00:34
|Pointers point to the locations in memory. 
 
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|00.38
|Pointers store the memory address. 

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| 00:41
|It also gives value stored at that address. 

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| 00:45
|Now, let us see an example on pointers.

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| 00:48
|Note that our file name is '''pointers_demo.c'''.

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| 00:54
|Let us go through the code now.

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| 00:56
|This is our header file as '''stdio.h'''.

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| 01:00
|This is our '''main()''' function.

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| 01:03
|Here we have '''long integer num''', assigned value '''10.'''

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| 01:09
|Then we have declared a pointer '''ptr'''. 

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| 01:12
|Asterisk sign is used to declare a pointer. 

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| 01:16
|This pointer can point to type '''long  int. '''

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| 01:20
|In the 'printf' statement, ampersand is used for retrieving memory address of the variable. 

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|01:28
|So, ampersand num (&num) will give the memory address of '''num'''. 

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| 01:33
|This statement will print the address of the variable num. 

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| 01:37
|Over here, ptr stores the address of num. 

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| 01:41
|This statement will print the address of ptr. 

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| 01:45
|'''sizeof()''' function will give the size of ptr. 

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|01:49
|This is will give the value of ptr. 

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|01:51
|That is the memory address of num. 

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|01:54
|And here asterisk ptr will give the value at the address. 

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|01:59
|So, using asterisk will not give the memory address. 

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|02:03
|Instead it will give the value. 

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|02:06
|'''%ld''' is a format specifier for the '''long int'''.

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|02:10
|Now, let us execute the program.

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|02:13
|Open the terminal window by pressing '''Ctrl, Alt''' and '''T''' keys simultaneously on your keyboard.

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|02:21
|To compile, type '''gcc space  pointers underscore demo dot c space hyphen o space point'''

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|02:32
|Press '''Enter'''.

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|02:34
|Type '''dot slash point'''. Press '''Enter'''.

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|02:39
|The output is displayed.

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| 02:42
|We see that the num address and ptr value is same 

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| 02:48
| where as memory address of num and ptr are different. 

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| 02:53
|Then the size of pointer is '''8 bytes.''' 

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| 02:57
| Also the value pointed by '''ptr''' is 10 which was assigned to '''num.''' 

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| 03:03
| Now let us see the same program in  C++. 

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| 03:07
| Note that our file name is '''pointer underscore demo.cpp'''.

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| 03:13
| Here we have a few changes like the header file as '''iostream'''.

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| 03:19
|Then we are using the '''std namespace'''.

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| 03:23
|And here we have the '''cout''' function in place of printf() function.

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| 03:28
|Rest all the things are similar.

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| 03:30
|Let us execute the program. Come back to our terminal.

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| 03:34
|To compile, type '''g++ space pointers_demo.cpp space hyphen o space point1''', press Enter.

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| 03:50
|Type '''dot slash point1''', press '''Enter'''.

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| 03:55
| We can see that the output is similar to our C program.

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| 04:00
|This brings us to the end of this tutorial.

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| 04:03
| Come back to our slide.

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| 04:05
|Let us summarize.

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| 04:06
|In this tutorial, we learnt:

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| 04:08
|About the pointer. 

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| 04:10
|To create a pointer. 

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| 04:12
|And operation on pointer. 

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| 04:14
|As an assignment, write a C and C++ program 

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| 04:18
|to declare a variable and pointer. 

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| 04:21
| Store the address of variable in the pointer. 

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| 04:24
|And print the value of the pointer. 

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| 04:27
|Watch the video available at the link shown below.

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| 04:30
|It summarizes the Spoken Tutorial project. 

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| 04:33
|If you do not have good bandwidth, you can download and watch it. 

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| 04:37
|The Spoken Tutorial Project Team: 

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| 04:39
|Conducts workshops using spoken tutorials. 

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|04:43
|Gives certificates to those who pass an online test. 

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| 04:47
|For more details, please write to contact@spoken-tutorial.org. 

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| 04:53
|Spoken Tutorial Project is a part of the Talk to a Teacher project. 

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| 04:58
|It is supported by the National Mission on Education through ICT, MHRD, Government of India.

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| 05:06
|More information on this mission is available at the link shown below.

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| 05:10
| This is Ashwini Patil from IIT Bombay, signing off. 

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| 05:14
|Thank You for joining.