Difference between revisions of "C-and-C++/C2/Functions/English-timed"
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|Every program consists of one or more functions. | |Every program consists of one or more functions. | ||
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|This is called as functions without arguments. | |This is called as functions without arguments. | ||
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|Let us see a program using void. | |Let us see a program using void. | ||
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| − | |Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously. | + | |Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously. |
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|We see an error at line no 10. | |We see an error at line no 10. | ||
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|too few arguments to function 'int add (int, int)' | |too few arguments to function 'int add (int, int)' | ||
Revision as of 14:50, 3 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
|
| 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 the 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
