C-and-C++/C2/Functions/English-timed
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Revision as of 17:46, 9 July 2014 by Pratik kamble (Talk | contribs)
Time | Narration |
00:01 | Welcome to the spoken tutorial on Functions in C and C++ |
00:06 | In this tutorial we will learn, |
00:09 | What is a function |
00:11 | Syntax of a function |
00:13 | Significance of return statement |
00:16 | We will do this through examples. |
00:18 | We will also see some common errors and their solutions. |
00:22 | To record this tutorial, I am using, |
00:25 | Ubuntu Operating System version 11.10 |
00:29 | gcc and g++ Compiler version 4.6.1 . |
00:35 | Let us start with the introduction to functions |
00:39 | A 'function is a self-contained program executing a specific task. |
00:45 | Every program consists of one or more functions. |
00:49 | Once executed, the control will be returned back from where it was accessed. |
00:55 | Let us see the syntax for function. |
00:59 | ret-type defines the type of data that the function returns. |
01:05 | fun_name defines the name of the function. |
01:09 | parameters is the list of variable names and their types. |
01:14 | We can specify an empty parameter list. |
01:18 | This is called as functions without arguments. |
01:21 | And this is called as functions with arguments. |
01:26 | Let us see a program using void. |
01:29 | I have already typed the program on the editor. |
01:32 | So I will open it. |
01:35 | Note that our filename is function. |
01:38 | And I have saved the file with the extentsion .c |
01:43 | Let me explain the code. |
01:45 | This is our header file. |
01:47 | Before using any function, it must be defined. |
01:51 | Here we have defined a function called add. |
01:54 | Note that add function is without any arguments. |
01:58 | And the return type is void. |
02:01 | There are two types of functions- |
02:03 | User-defined that is our add function and |
02:06 | Pre-defined that is printf and main function |
02:12 | Here we have initialized a and b by assigning them values as 2 and 3 |
02:19 | Here we have declared a variable c. |
02:21 | Then we add the values of a and b. |
02:24 | The result is stored in c. |
02:27 | Then we print the result. |
02:29 | This is our main function. |
02:32 | Here we call the add function. |
02:34 | The addition operation will be performed and the result will be printed. |
02:39 | Now click on Save. |
02:42 | Let us execute the program. |
02:45 | Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously. |
02:53 | To compile, type gcc function dot c hyphen o fun |
03:00 | To execute, type ./fun (dot slash fun) |
03:05 | We see the output is displayed as Sum of a and b is 5 |
03:10 | Now come back to our program. |
03:13 | Functions contains special identifiers called as parameters or arguments. |
03:20 | Let us see the same example with arguments. |
03:23 | I will change a few things here. |
03:27 | Type int add(int a, int b) |
03:32 | Here we have declared a function add. |
03:36 | int a and int b are the arguments of the function add. |
03:41 | Let us delete this. |
03:42 | No need to initialize a and b here. |
03:46 | Delete the printf statement. |
03:49 | Type int main() |
03:52 | Let us declare a variable sum here. |
03:54 | Type int sum; |
03:57 | Then type sum = add(5,4); |
04:03 | Here we call the add function. |
04:05 | Then we pass the parameters as 5 and 4. |
04:10 | 5 will be stored in a and 4 will be stored in b. |
04:14 | The addition operation will be performed. |
04:18 | Let us now print the result. |
04:20 | Hence type here |
04:21 | printf(“Sum is %d\n”,sum); |
04:27 | Delete this, as we have already called the function above. |
04:32 | Type return 0; |
04:36 | A non-void function must use a return statement that returns a value. |
04:41 | Click on Save |
04:43 | Let us execute the program. |
04:45 | Come back to our terminal. |
04:48 | Now compile the program as before. |
04:50 | Let us execute. |
04:52 | The output is displayed as Sum is 9 |
04:57 | Now let us see how to execute the same program in C++. |
05:02 | Come back to our program. |
05:04 | Let me change a few things here. |
05:07 | First press Shift, Ctrl and S keys simultaneously. |
05:12 | Now save the file with .cpp extension. |
05:18 | Click on Save. |
05:19 | First we will change the header file as <iostream> |
05:24 | We will include the using statement here. |
05:28 | The function declaration is same in C++. |
05:32 | So there is no need to change anything here. |
05:37 | Now replace the printf statement with the cout statement, as we use cout<< function to print a line in C++. |
05:48 | We don't need the format specifier and \n here. |
05:52 | Delete the comma. |
05:54 | Now, type two opening angle brackets |
05:58 | After sum , again type two opening angle brackets. |
06:03 | Within double quotes, type backslash n. |
06:07 | Delete this closing bracket. |
06:09 | Now Click on Save. |
06:11 | Let us compile the program. |
06:14 | Come back to our terminal. |
06:16 | Type g++ function dot cpp hyphen o fun1 |
06:23 | Here we have fun1, this is because we don't want to overwrite the output file fun. |
06:31 | Press Enter. |
06:34 | Type ./fun1 |
06:38 | The output is displayed as: Sum is 9 |
06:42 | Now we will see the common errors which we can come across. |
06:47 | Suppose here, we type x in place of 4. |
06:51 | I will retain the rest of the code as it is. |
06:55 | Click on Save. |
06:58 | Let us compile the program. |
07:02 | We see an error at line no. 10. |
07:06 | x was not declared in this scope. |
07:09 | This is because x is a character variable. |
07:13 | It was not declared anywhere. |
07:15 | And our add function has integer variable as an argument. |
07:21 | So, there is a mismatch in return type and return value. |
07:25 | Now come back to our program. |
07:27 | Let us fix the error. |
07:30 | Type 4 at line no. 10. |
07:32 | Click on Save. |
07:35 | Let us execute again. |
07:37 | Let me clear the prompt. |
07:40 | Compile the program as before. |
07:42 | Yes! it is working. |
07:45 | Now we will see another common error which we can come across. |
07:50 | Suppose here we pass only one parameter. |
07:55 | Delete 4. |
07:56 | Click on Save |
07:58 | Switch to the terminal. |
08:00 | Let us compile. |
08:01 | We see an error at line no 10. |
08:06 | too few arguments to function 'int add (int, int)' |
08:11 | Switch back to our program. |
08:14 | You can see here we have two parameters |
08:19 | int a and int b. |
08:22 | And here we are passing only one parameter. |
08:25 | Hence it is giving an error. |
08:27 | Let us fix the error. |
08:29 | Type 4. |
08:31 | Click on Save . |
08:34 | Switch to the terminal. |
08:36 | Let us execute again. |
08:39 | Yes it is working! |
08:42 | Come back to our slides. |
08:44 | To summarise, in this tutorial we have learnt - |
08:49 | Function |
08:50 | Syntax of function |
08:51 | Function without arguments |
08:53 | Eg- void add() |
08:55 | Function with arguments |
08:57 | Eg- int add(int a and int b) |
09:02 | As an assignment- |
09:03 | Write a program to calculate the square of a number. |
09:07 | Watch the video available at the link shown below |
09:11 | It summarizes the Spoken Tutorial project |
09:14 | If you do not have good bandwidth, you can download and watch it |
09:18 | The Spoken Tutorial Project Team |
09:21 | Conducts workshops using spoken tutorials |
09:24 | Gives certificates to those who pass an online test |
09:28 | For more details, please write to, contact@spoken-tutorial.org |
09:35 | Spoken Tutorial Project is a part of Talk to a Teacher project |
09:40 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
09:47 | More information on this Mission is available at the link shown below |
09:52 | This is Ashwini Patil from IIT Bombay |
09:55 | Thank You for joining. |
Contributors and Content Editors
Ashwini, Kavita salve, Krupali, PoojaMoolya, Pratik kamble, Sandhya.np14