Difference between revisions of "C-and-C++/C2/Functions/English-timed"

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Revision as of 21:19, 1 February 2015

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 file name is function.
01:38 And I have saved the file with the extension .c (dot 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 contain 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 summarize, 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, 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

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