Difference between revisions of "C-and-C++/C4/Function-Call/English-timed"

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

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

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|In this tutorial we will learn about type of function calls namely

|In this tutorial we will learn about type of function calls namely

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|call by value.     

|call by value.     

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|call by reference.  

|call by reference.  

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|We will do this through an example.  

|We will do this through 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  

|'''gcc''' and '''g++''' Compiler version 4.6.1  

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| Let us start with the introduction to '''functions call by value'''

| Let us start with the introduction to '''functions call by value'''

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|It is a method of passing '''arguments''' to the function.  

|It is a method of passing '''arguments''' to the function.  

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| When we pass a variable by value it makes a copy of the variable.

| When we pass a variable by value it makes a copy of the variable.

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|Before passing to the function.

|Before passing to the function.

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|Changes made to the arguments inside the function will remain in the function.  

|Changes made to the arguments inside the function will remain in the function.  

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|It will not be affected outside the function.  

|It will not be affected outside the function.  

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|Let us see a program on function call by value.  

|Let us see a program on function call by value.  

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|I have already typed the program on the editor. I will just open it.   

|I have already typed the program on the editor. I will just open it.   

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| Please note our filename is '''callbyval.c. '''

| Please note our filename is '''callbyval.c. '''

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|In this program we will calculate the cube of a number. Let me explain the code now.  

|In this program we will calculate the cube of a number. Let me explain the code now.  

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|This is our '''header file'''

|This is our '''header file'''

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|Here we have function '''cube''' having an '''argument''' as '''int x. '''

|Here we have function '''cube''' having an '''argument''' as '''int x. '''

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|In this function we calculate the cube of '''x''' and return the value of '''x.  '''

|In this function we calculate the cube of '''x''' and return the value of '''x.  '''

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|This is our '''main function.'''

|This is our '''main function.'''

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|Here we give the value of '''n''' as '''8. n''' is an integer variable

|Here we give the value of '''n''' as '''8. n''' is an integer variable

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|Then we call the function '''cube.'''

|Then we call the function '''cube.'''

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|And print the value of '''n '''and the cube of n.

|And print the value of '''n '''and the cube of n.

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|And this is our return statement.  

|And this is our return statement.  

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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 callbyval.c space hyphen o space val. Press Enter'''

|To compile , type '''gcc space callbyval.c space hyphen o space val. Press Enter'''

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|Now type '''./val '''(dot slash val).Press '''Enter'''

|Now type '''./val '''(dot slash val).Press '''Enter'''

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|The output is displayed as '''Cube of 8 is 512.'''

|The output is displayed as '''Cube of 8 is 512.'''

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|Now we will see function call by reference.  

|Now we will see function call by reference.  

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|Let us go back to our slides.  

|Let us go back to our slides.  

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|It is another method of passing '''arguments''' to the function.  

|It is another method of passing '''arguments''' to the function.  

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| This method copies the address of the argument instead of the value.   

| This method copies the address of the argument instead of the value.   

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|Changes made to the arguments inside a function can affect them outside.  

|Changes made to the arguments inside a function can affect them outside.  

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|In this we need to declare the arguments as pointer type.  

|In this we need to declare the arguments as pointer type.  

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| Let us see an example on function call by reference.   

| Let us see an example on function call by reference.   

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|Note that our filename is '''callbyref.c'''

|Note that our filename is '''callbyref.c'''

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

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

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|Then we have function '''swap'''

|Then we have function '''swap'''

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|This function will exchange the values of the variables.  

|This function will exchange the values of the variables.  

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|Value of a will be stored in value of b and vice-versa.  

|Value of a will be stored in value of b and vice-versa.  

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|You can see that the '''arguments''' passed in the function are '''pointer type.'''

|You can see that the '''arguments''' passed in the function are '''pointer type.'''

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|Here we have declared an '''integer''' variable '''t.'''

|Here we have declared an '''integer''' variable '''t.'''

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|First value of a is stored in t.

|First value of a is stored in t.

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|Then value of b is stored in a.

|Then value of b is stored in a.

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| And then value of t is stored in b  

| And then value of t is stored in b  

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| Like this the values are exchanged.  

| Like this the values are exchanged.  

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|This is our '''main''' function.  

|This is our '''main''' function.  

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|Here we have declared two integer variables as i and j .  

|Here we have declared two integer variables as i and j .  

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|Then we take the values of i and j as user inputs.  

|Then we take the values of i and j as user inputs.  

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|Ampersand i and Ampersand j will give the memory address of i and j.

|Ampersand i and Ampersand j will give the memory address of i and j.

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|First we print the values before swapping.  

|First we print the values before swapping.  

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|Then we call the function '''swap'''

|Then we call the function '''swap'''

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|And then we print the values after swapping.  

|And then we print the values after swapping.  

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|And this is our return statement.  

|And this is our return statement.  

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| Now let us execute the program  

| Now let us execute the program  

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| Switch back to our terminal  

| Switch back to our terminal  

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|To compile type '''gcc space callbyref dot c space hyphen o space ref'''. Press Enter

|To compile type '''gcc space callbyref dot c space hyphen o space ref'''. Press Enter

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|Now type '''dot slash ref'''. Press Enter

|Now type '''dot slash ref'''. Press Enter

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|We see, enter the values I will enter as 6 and 4

|We see, enter the values I will enter as 6 and 4

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|The output is displayed as,before swapping 6 and 4

|The output is displayed as,before swapping 6 and 4

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|After swapping 4 and 6

|After swapping 4 and 6

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|Now let us see how to execute the same program in C++  

|Now let us see how to execute the same program in C++  

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|I have the code, lets go through it.  

|I have the code, lets go through it.  

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|This is the second program function callbyreference .  

|This is the second program function callbyreference .  

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|Note that our filename is '''callbyref.cpp'''

|Note that our filename is '''callbyref.cpp'''

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|Let us go through the code  

|Let us go through the code  

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|This is our header file as '''iostream '''

|This is our header file as '''iostream '''

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

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

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|The function declaration is same in C++.  

|The function declaration is same in C++.  

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|In this we pass the arguments as ampersand x and ampersand y.  

|In this we pass the arguments as ampersand x and ampersand y.  

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| This will give the memory address of x and y.  

| This will give the memory address of x and y.  

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|Then we swap the values.  

|Then we swap the values.  

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|Rest of the code is similar to our C code.  

|Rest of the code is similar to our C code.  

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|The '''printf''' statement is replaced by cout and the scanf statement is replaced by cin   

|The '''printf''' statement is replaced by cout and the scanf statement is replaced by cin   

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|Now let us execute the program. Come back to our terminal  

|Now let us execute the program. Come back to our terminal  

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|To compile type; '''g++ space callbyref.cpp space hyphen o space ref1''', press Enter

|To compile type; '''g++ space callbyref.cpp space hyphen o space ref1''', press Enter

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|Now Type  '''dot slash ref1,''' Press Enter

|Now Type  '''dot slash ref1,''' Press Enter

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|Here it is displayed as:

|Here it is displayed as:

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|Enter values of a and b

|Enter values of a and b

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|I will enter as 4 and 3

|I will enter as 4 and 3

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|The output is displayed  

|The output is displayed  

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|'''Before swapping a and b 4 and 3'''

|'''Before swapping a and b 4 and 3'''

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|'''After swapping a and b  3 and 4'''

|'''After swapping a and b  3 and 4'''

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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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|Let us go back to our slides.  

|Let us go back to our slides.  

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|Let us summarize, In this tutorial we learn't:  

|Let us summarize, In this tutorial we learn't:  

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|Function call by value.  

|Function call by value.  

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|And Function call by reference.  

|And Function call by reference.  

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|As an assignment  

|As an assignment  

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|Write a similar program to calculate the cube of a number.  

|Write a similar program to calculate the cube of a number.  

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|Using call by value in C++.  

|Using call by value in C++.  

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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.