Difference between revisions of "C-and-C++/C4/Understanding-Pointers/English-timed"

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|Welcome to the spoken tutorial on '''Pointers in C and C++ '''

|Welcome to the spoken tutorial on '''Pointers in C and C++ '''

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|In this tutorial we will learn,   

|In this tutorial we will learn,   

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|Pointers.  

|Pointers.  

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|To create Pointers.  

|To create Pointers.  

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|And operations on Pointers.  

|And operations on Pointers.  

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| We will do this with the help of an example

| We will do this with the help of an example

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|To record this tutorial I am using Ubuntu operating system version 11.10

|To record this tutorial I am using Ubuntu operating system version 11.10

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| gcc and g++ compiler version 4.6.1 on Ubuntu

| gcc and g++ compiler version 4.6.1 on Ubuntu

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|Let us start with an introduction to pointers

|Let us start with an introduction to pointers

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|Pointers point to the locations in memory.  

|Pointers point to the locations in memory.  

   

   

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|It also gives value stored at that address.  

|It also gives value stored at that address.  

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|Now, let us see an example on pointers

|Now, let us see an example on pointers

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|Note that our file name is '''pointers_demo.c'''

|Note that our file name is '''pointers_demo.c'''

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|Let us go through the code now

|Let us go through the code now

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|This is our header file as '''stdio.h'''

|This is our header file as '''stdio.h'''

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|This is our main function

|This is our main function

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|Here we have '''long integer num''' assigned value '''10.'''

|Here we have '''long integer num''' assigned value '''10.'''

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|Then we have declared a pointer ptr.  

|Then we have declared a pointer ptr.  

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|Asterisk sign is used to declare a pointer.  

|Asterisk sign is used to declare a pointer.  

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|This pointer can point to type '''long  int. '''

|This pointer can point to type '''long  int. '''

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|In the printf statement ampersand is used for retrieving memory address of the variable.  

|In the printf statement ampersand is used for retrieving memory address of the variable.  

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|So ampersand num will give the memory address of num.  

|So ampersand num will give the memory address of num.  

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|This statement will print the address of the variable num.  

|This statement will print the address of the variable num.  

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|Over here ptr stores the address of num.  

|Over here ptr stores the address of num.  

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|This statement will print the address of ptr.  

|This statement will print the address of ptr.  

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|Sizeof function will give the size of ptr.  

|Sizeof function will give the size of ptr.  

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|This is will give the value of ptr.  

|This is will give the value of ptr.  

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|That is the memory address of num.  

|That is the memory address of num.  

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

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

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|So using asterisk will not give the memory address.  

|So using asterisk will not give the memory address.  

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|Instead it will give the value.  

|Instead it will give the value.  

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|%ld is a format specifier for the long int

|%ld is a format specifier for the long int

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|Now, let us execute the program

|Now, let us execute the program

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|Open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard

|Open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard

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|To compile type '''gcc space  pointers underscore demo dot c space hyphen o space point'''

|To compile type '''gcc space  pointers underscore demo dot c space hyphen o space point'''

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|Press '''Enter'''

|Press '''Enter'''

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|Type '''dot slash point'''. Press '''Enter'''

|Type '''dot slash point'''. Press '''Enter'''

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|The output is displayed

|The output is displayed

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|We see that the num address and ptr value is same.  

|We see that the num address and ptr value is same.  

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| Where as memory address of num and ptr are different.  

| Where as memory address of num and ptr are different.  

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|Then the size of pointer is '''8 bytes.'''  

|Then the size of pointer is '''8 bytes.'''  

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

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

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

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

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

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

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| Here we have few changes like the header file as '''iostream'''

| Here we have few changes like the header file as '''iostream'''

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|Then we are using the '''std namespace'''

|Then we are using the '''std namespace'''

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|And we have the cout function in place of printf function

|And we have the cout function in place of printf function

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|Rest all the things are similar

|Rest all the things are similar

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

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

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

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

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|Type '''dot slash point1''', press '''Enter'''

|Type '''dot slash point1''', press '''Enter'''

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| We can see that the output is similar to our C program

| We can see that the output is similar to our C program

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|This brings us to the end of this tutorial.

|This brings us to the end of this tutorial.

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| Come back to our slide

| Come back to our slide

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|Let us summarize

|Let us summarize

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|In this tutorial, we learnt

|In this tutorial, we learnt

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|About the pointer.  

|About the pointer.  

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|To create a pointer.  

|To create a pointer.  

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|And operation on pointer.  

|And operation on pointer.  

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|As an assignment, write a C and C++ program,  

|As an assignment, write a C and C++ program,  

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|To declare a variable and pointer.  

|To declare a variable and pointer.  

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| Store the address of variable in the pointer.  

| Store the address of variable in the pointer.  

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|And print the value of the pointer.  

|And print the value of the pointer.  

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|Watch the video available at the link shown below

|Watch the video available at the link shown below

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|It summarizes the Spoken Tutorial project  

|It summarizes the Spoken Tutorial project  

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|If you do not have good bandwidth, you can download and watch it  

|If you do not have good bandwidth, you can download and watch it  

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|The Spoken Tutorial Project Team  

|The Spoken Tutorial Project Team  

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|-

|Conducts workshops using spoken tutorials  

|Conducts workshops using spoken tutorials  

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|Gives certificates to those who pass an online test  

|Gives certificates to those who pass an online test  

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

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

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|Spoken Tutorial Project is a part of the Talk to a Teacher project  

|Spoken Tutorial Project is a part of the Talk to a Teacher project  

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

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

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|More information on this Mission is available at the link shown below

|More information on this Mission is available at the link shown below

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| This is Ashwini Patil from IIT Bombay signing off  

| This is Ashwini Patil from IIT Bombay signing off  

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|Thank You for joining.

|Thank You for joining.