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

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Revision as of 12:58, 25 February 2014

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

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