Difference between revisions of "C-and-C++/C2/Functions/English-timed"
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| − | + | type int sum; | |
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Revision as of 11:30, 10 October 2013
| Time' | Narration
|
| 00.01 | Welcome to the spoken tutorial on Functions in C and C++ |
| 00.07 | In this tutorial we will learn, |
| 00.10 | What is a function |
| 00.12 | Syntax of a function |
| 00.15 | Significance of a return statement |
| 00.18 | Few example on functions. |
| 00.20 | We will also see some common errors and their solutions. |
| 00.25 | To record this tutorial, I am usingUbuntu Operating system version 11.10 |
| 00.33 | gcc and g++ Compiler version 4.6.1 |
| 00.40 | Let us start with the introduction to functions |
| 00.43 | A function is a self-contained program executing a specific task |
| 00.50 | Every program consists of one or more functions |
| 00.56 | Once executed the control will be returned back from where it was accessed |
| 01.03 | Now we will see the syntax for the function |
| 01.18 | ret-type' defines the type of data that the function returns |
| 01.12 | fun_name is the name of the function |
| 01.16 | parameters is the list of variable names and their types |
| 01.20 | Another syntax for functions is ret_type function name an empty parameter list
|
| 01.30 | This is called as functions without arguments. |
| 01.35 | And This is called as functions with arguments. |
| 01.40 | Let us move on to our program |
| 01.43 | I have already typed the program on the editor |
| 01.46 | Let me open it |
| 01.50 | Note that our filename is void function.c In this program we will calculate the sum of two numbers using function.. |
| 02.03 | Let me explain the code now.
|
| 02.06 | This is our header file |
| 02.09 | Before using any function it must be defined |
| 02.14 | Here we have declared a function called add |
| 02.18 | Note that add function is without any arguments |
| 02.22 | And the return type is void |
| 02.25 | There are two types of functions |
| 02.27 | First User-defined function that is our add function and |
| 02.33 | Pr-defined function that is printf and main function |
| 02.39 | Here we have initialized a and b by assigning them values 2 and 3 |
| 02.47 | Then we have declared a variable c |
| 02.51 | we add the values of a and b |
| 02.53 | The result is stored in c |
| 02.57 | Then we print the result |
| 03.00 | This is our main function |
| 03.03 | Inside the main function, we call the add function |
| 03.07 | The addition operation will be performed and the result will be printed. |
| 03.13 | Now click on Save |
| 03.15 | Let us execute the program |
| 03.17 | Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard |
| 03.28 | To compile type |
| 03.29 | 'gcc void function.c -o void and press enter |
| 03.40 | To execute, type
./void |
| 03.45 | The output is displayed asSum of a and b is 5 |
| 03.50 | Now come back to our program |
| 03.53 | Functions contains special identifiers called as parameters or arguments |
| 04.00 | Now we will see the same example with arguments |
| 04.03 | I will change a few things here. Press shift Ctrl & S key simultaneously on your keyboard. |
| 04.14 | Now save the file as Function.c .Click on Save. |
| 04.24 | Replace the void key word with int and within the brakets type int a, int b |
| 04.34 | Click on save
|
| 04.37 | Here int a and int b are the arguments of the function add
type int sum; |
| 04.44 | Now delete this |
| 04.47 | No need to initialize a and b here. Now replace the void keyword again with the int keyword and click on save
|
| 04.58 | Let us declare a variable sum here |
| 05.01 | type int sum and the semicolon; |
| 05.05 | Press enter |
| 05.06 | And type sum = add(5,4); |
| 05.19 | Here we call the add function |
| 05.22 | Then we pass the arguments as 5 and 4 |
| 05.26 | 5 will be stored in a and 4 will be stored in b |
| 05.31 | The addition operation will be performed |
| 05.34 | The returned value c will be stored in sum. |
| 05.38 | Now delete this add as we have already called the function above |
| 05.44 | And Type |
| 05.45 | return 0; Now click on save |
| 05.51 | A non-void function must use a return statement that returns a value. |
| 05.58 | Let us execute the program |
| 06.00 | Come back to a terminal |
| 06.03 | Type gcc function.c -o fun and press enter
|
| 06.13 | To execute
./fun press enter |
| 06.19 | the output is displayed as |
| 06.21 | The Sum of a & b is 9 |
| 06.25 | NOW WE WILL EXECUTE THE SAME PROGRAM IN C++ |
| 06.29 | Come back to our program. I will edit the same code again press Shift'Ctrl & S key simultaneously on your keyboard
|
| 06.41 | Now Save the file with an extension .cpp and click on save |
| 06.47 | Let us change the header file as iostream |
| 06.52 | Now include the using statement. Click on save |
| 07.00 | The function declaration is same in C++ |
| 07.04 | So there is no need to change anything here |
| 07.07 | Now replace the printf statement with the cout statement
|
| 07.13 | Delete the format specifier and \n |
| 07.16 | delete the comma |
| 07.17 | Type two opening angle brackets. Delete the closing bracket here |
| 07.23 | Again type two opening angle brackets |
| 07.25 | and within the double quotes type backslash n |
| 07.29 | We use the cout function to print the line in C++ |
| 07.34 | Now Click on save |
| 07.37 | Let us exeute the program |
| 07.39 | Come back to our terminal |
| 07.42 | To compile, type g++ function.cpp -o fun1 |
| 07.52 | Here we have fun1, because we don't want to overwrite the output parameter fun for the file fun.c . |
| 08.02 | Now press Enter |
| 08.05 | To execute |
| 08.06 | Type./fun1 And press enter |
| 08.12 | The output is displayed as: |
| 08.14 | The sum of a & b is 9. |
| 08.16 | we can see that the output is similar to our c code |
| 08.20 | Let us see some common errors which we can come across. |
| 08.24 | Come back to our program. |
| 08.26 | Suppose here at line no-11 . I will type x in the place of 4. |
| 08.32 | I will retain the rest of the code as it is. |
| 08.36 | Now click on Save |
| 08.38 | Let us execute the program |
| 08.40 | Come back to our terminal. |
| 08.44 | Let us compile as before |
| 08.48 | We see an error |
| 08.50 | x was not declared in this scope. come back to our program |
| 08.54 | This is because x is a character variable |
| 08.58 | And our add function has integer variable as an argument |
| 09.04 | So there is a mismatch in return type and return value. |
| 09.08 | Now Let us fix the error
|
| 09.10 | Type 4 here. Click on Save |
| 09.15 | Let us execute |
| 09.17 | Come back to our terminal. Let me clear the prompt. |
| 09.21 | Let us compile as before, execute as before |
| 09.27 | Yes! it is working |
| 09.29 | now we will see another common error .Come back to our program |
| 09.34 | here we will pass only 1 argument |
| 09.39 | delete 4 |
| 09.40 | Now Click on Save . |
| 09.43 | Let us see, what happens come back to our terminal. |
| 09.47 | Let us compile as before
|
| 09.49 | We see error too few arguments to few functions int 'add'
|
| 09.54 | Come back to our program
|
| 09.56 | You can see here we have two argument int a and int b |
| 10.03 | And here we are passing only one argument. |
| 10.06 | Hence it is giving an error |
| 10.09 | Let us fix the error |
| 10.10 | Type 4 ,click on save |
| 10.13 | Let us execute again |
| 10.16 | Compile as before , execute as before. |
| 10.21 | Yes it is working!Now come back to our slide |
| 10.26 | Let us summaries ,In this tutorial we learn't |
| 10.29 | Functions |
| 10.31 | Syntax of function |
| 10.33 | Function without arguments: e.g ; void add() |
| 10.37 | Function with arguments: e.g ;int add( int a,int b) |
| 10.43 | As an assignment |
| 10.45 | Write a program to calculate the square of a number using function. |
| 10.50 | Watch the video available at http://spoken-tutorial.org /What\_is\_a\_Spoken\_Tutorial |
| 10.53 | It summarises the Spoken Tutorial project |
| 10.56 | If you do not have good bandwidth, you can download and watch it |
| 11.01 | The Spoken Tutorial Project Team |
| 11.03 | Conducts workshops using spoken tutorials |
| 11.07 | Gives certificates to those who pass an online test |
| 11.11 | For more details, please write to contact@spoken-tutorial.org |
| 11.19 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 11.23 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
| 11.30 | More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro |
| 11.35 | This is Ashwini Patil from IIT Bombay |
| 11.39 | Thank You for joining |
Contributors and Content Editors
Ashwini, Kavita salve, Krupali, PoojaMoolya, Pratik kamble, Sandhya.np14
