Difference between revisions of "C-and-Cpp/C2/Functions/English-USA"
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| − | | | + | |What is a '''function''' |
|- | |- | ||
| 00:11 | | 00:11 | ||
| − | | | + | |Syntax of a '''function''' |
|- | |- | ||
| 00:13 | | 00:13 | ||
| − | | | + | |Significance of '''return statement''' |
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| Line 233: | Line 233: | ||
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| − | | 03: | + | | 03:43 |
|No need to initialize a and b here. | |No need to initialize a and b here. | ||
| Line 281: | Line 281: | ||
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| − | | 04: | + | | 04:22 |
|'''printf(“Sum is %d\n”, sum);''' | |'''printf(“Sum is %d\n”, sum);''' | ||
| Line 509: | Line 509: | ||
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| − | | 07: | + | | 07:57 |
|Click on '''Save'''. | |Click on '''Save'''. | ||
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| − | | 07: | + | | 07:59 |
|Switch to the terminal. | |Switch to the terminal. | ||
|- | |- | ||
| − | | 08: | + | | 08:01 |
| Let us compile. | | Let us compile. | ||
|- | |- | ||
| − | | 08: | + | | 08:03 |
|We see an error at line no 10. | |We see an error at line no 10. | ||
| Line 581: | Line 581: | ||
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| − | | 08: | + | | 08:48 |
| − | | | + | |'''function''' |
|- | |- | ||
| 08:50 | | 08:50 | ||
| − | | | + | |Syntax of '''function''' |
|- | |- | ||
| − | | 08: | + | | 08:52 |
| − | | | + | |'''function without arguments''' |
|- | |- | ||
| − | | 08: | + | | 08:54 |
|Eg- void add() | |Eg- void add() | ||
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| − | | 08: | + | | 08:56 |
|Function with arguments | |Function with arguments | ||
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| − | | 08: | + | | 08:58 |
|Eg- int add(int a, int b) | |Eg- int add(int a, int b) | ||
|- | |- | ||
| 09:02 | | 09:02 | ||
| − | |As an assignment | + | |As an assignment, write a program to calculate the square of a number. |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
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Latest revision as of 13:23, 23 March 2017
| 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. |
| 03:43 | 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 |
| 04:22 | 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. |
| 07:57 | Click on Save. |
| 07:59 | Switch to the terminal. |
| 08:01 | Let us compile. |
| 08:03 | 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 - |
| 08:48 | function |
| 08:50 | Syntax of function |
| 08:52 | function without arguments |
| 08:54 | Eg- void add() |
| 08:56 | Function with arguments |
| 08:58 | Eg- int add(int a, int b) |
| 09:02 | As an assignment, 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 Jean Bonnet from IIT Bombay. |
| 09:55 | Thank You for joining. |
