C-and-C++/C2/Functions/English-timed
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Time | Narration
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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 .
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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.
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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.
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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.
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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-
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02.03 | User-defined that is our add function and |
02.06 | Pre-defined that is printf and main function
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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
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03.00 | To execute, type ./fun
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03.05 | We see the output is displayed as Sum of a and b is 5
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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)
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03.32 | Here we have declared a function add.
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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()
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03.52 | Let us declare a variable sum here.
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03.54 | Type int sum;
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03.57 | Then type sum = add(5,4);
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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;
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04.36 | A non-void function must use a return statement that returns a value.
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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.
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04.52 | The output is displayed as Sum is 9
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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.
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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>
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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.
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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 the terminal. |
06.16 | Type g++ function dot cpp hyphen o fun1
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06.23 | Here we have fun1, this is because we don't want to overwrite the output file fun.
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06.31 | Press Enter. |
06.34 | Type ./fun1
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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.
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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.
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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
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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