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Time Narration
00:02 Welcome to the spoken tutorial on First C++ program.
00:07 In this tutorial I am going to explain,
00:10 How to write a C++ program
00:13 How to compile it, How to execute it
00:17 We will also explain some common errors and their solution.
00:22 To record this tutorial, I am using Ubuntu operating system version 11.10 and
00:29 G++ Compiler version 4.5.2 on Ubuntu.
00:35 To practice this tutorial,
00:37 You should be familiar with Ubuntu Operating System and an Editor
00:44 Some editors are 'vim' and 'gedit'.
00:48 I am using 'gedit' in this tutorial.
00:50 For relevant tutorial please visit our website which is as shown.
00:56 Let me tell you how to write a C++ program through an example.
01:01 Open the terminal Window using Ctrl, Alt and T keys simultaneously on your keyboard.
01:09 To open the text editor, type on the terminal.
01:13 “gedit” space “talk” dot “.cpp” space ampersand “&” sign.
01:21 We use the “&” to free up the prompt.
01:25 Please note that all the C++ files will have the extension “.cpp”.
01:31 Now Press Enter,
01:33 the text editor has opened.
01:35 Let us start to write a program.
01:38 Type double slash “//” space “My first C++ program”.
01:44 Here, double slash is used to comment the line.
01:49 Comments are used to understand the flow of program.
01:52 It is useful for documentation.
01:55 It gives us information about the program.
01:59 The double slash is called as single line comment. Now press Enter.
02:05 Type (hash) “#include”, space, opening angle bracket, closing angle bracket .
02:13 It is a good practice to complete the brackets first, and then start writing inside it.
02:20 Now Inside the bracket, type “iostream” .
02:23 Here iostream is a header file.
02:26 This file includes the declaration of standard input output functions in C++. Now press Enter.
02:35 Type “using” space “namespace” space “std” and a semicolon “;” .
02:45 The using statement informs the compiler that you want to use the std namespace.
02:52 The purpose of namespace is to avoid name collisions.
02:56 It is done by localizing the names of identifiers.
03:00 It creates a declarative region and defines a scope.
03:05 Anything defined within a namespace is in the SCOPE of that namespace.
03:11 Here std is the namespace in which entire standard C++ library is declared. Now press Enter.
03:20 Type “int” space “main” opening bracket, closing bracket .
03:26 main is a special function.
03:30 It denotes that the execution of the program begins from this line.
03:34 The opening and the closing bracket is called as Parenthesis.
03:39 Parenthesis followed by main tells the user that main is a function.
03:45 Here, the int main() function takes no arguments and returns a value of type integer.
03:52 We will learn about data types in another tutorial.
03:56 Now let us switch to the slides to know more about main function.
04:02 Every program should have one main function.
04:04 There should NOT be more than one “main” function.
04:09 Otherwise the compiler cannot locate the beginning of the program.
04:13 The empty pair of parentheses indicates that main has no arguments.
04:19 The concept of arguments will be discussed in the upcoming tutorials.
04:24 Now come back to our program. Press Enter.
04:29 Type opening curly bracket “{”.
04:32 The opening curly bracket marks the beginning of the function main().
04:37 Then Type closing curly bracket “}”.
04:40 The closing bracket indicates the end of the function main().
04:45 Now, inside the bracket press enter twice.
04:49 Move the cursor one line up.
04:51 Indentation makes the code easier to read.
04:54 It also helps to locate errors faster.
04:58 So let us give a space here.
05:01 And type “cout” space two opening angle bracket '.
05:07 Here cout is a standard C++ function to print the output on the terminal.
05:14 Now after the brackets, type within double quotes.
05:18 Anything within the double quotes, in the cout functions, will be printed.
05:24 Now inside a quote type“Talk to a teacher backslash n” (\n).
05:31 Here \n signifies newline.
05:35 As a result, after execution of the cout function, the cursor moves to the new line.
05:41 Every C++ statement must end with a semicolon.
05:45 Hence type it at the end of this line.
05:48 Semicolon acts as a statement terminator. Now press Enter.
05:53 Give a space here and Type “return” space “0” and a semicolon “;”.
06:00 This statement returns the integer zero.
06:03 An integer has to be returned for this function because the function type is int.
06:10 The return statement marks the end of executable statements.
06:14 We will learn more about the returned values in another tutorial.
06:20 Now click on “Save” button to save the file.
06:23 It is a good habit to save files frequently.
06:26 This will protect you from sudden power failures.
06:30 It will also be useful in case the applications were to crash.
06:34 Let us now compile the program.
06:36 Come back to our terminal.
06:39 Type “g++” space “talk.cpp” space hyphen “-o” space “output”.
06:49 Here g++ is the compiler used to compile C++ programs.
06:55 talk.cpp is our filename.
06:59 hyphen -o output says that the executable should go to the file "output".
07:05 Now press Enter.
07:07 We see that the program is compiled.
07:10 By typing ls space hyphen lrt, we can see that output is the last file to be created.
07:19 Let us execute a program, type “./output” (dot slash output).
07:24 And Press Enter.
07:27 Here the output is displayed as “Talk to a teacher”.
07:30 Now let us see the common errors which we can come across.
07:35 Switch back to our text editor.
07:38 Suppose here we miss the }(closing curly bracket)
07:42 now save the file.
07:44 Let us execute. Come back to our terminal.
07:48 Now compile and run the program using the command we used before. We see an error.
07:55 We see that there is an error at line no.7 in our talk.cpp file that "expected curly bracket at the end of input".
08:07 Now Come back to our text editor .
08:09 As I said before, the closing curly bracket marks the end of the function main
08:14 Hence re-insert the bracket here. Now Save the file.
08:19 Let us execute it again.
08:21 You can recall the previously entered commands by using up arrow key.
08:26 That is what I did now.
08:30 Yes, it is working.
08:32 I will show you another common error.
08:35 Let us switch back to our text editor.
08:37 Now, suppose here we missed std.
08:41 Let us save the file.
08:44 Come back to our terminal .
08:46 Let us compile .
08:48 We see that there is an error at line no.3 and line no.6 in our talk.cpp file.
08:56 That "expected identifier before 'semicolon' " and " 'cout' was not declared in this scope".
09:05 As cout is the standard C++ library function.
09:09 and the entire C++ library function is defined under std namespace .
09:15 Hence it is giving an error.
09:18 Let us now fix the error.Come back to our Text editor. Type std here.
09:23 Let us save it.
09:25 Let us compile it again.
09:29 Yes, it is working.As an assignment,
09:33 write a program to print your name and city.
09:37 We used single line comment in this tutorial.
09:40 Now just try to give a multiline comment.
09:44 Watch the video available at the link shown below.
09:46 It summarizes the Spoken Tutorial project.
09:48 If you do not have good bandwidth, you can download and watch it.
09:53 The Spoken Tutorial Project Team:
09:55 Conducts workshops using spoken tutorials.
09:58 Gives certificates to those who pass an online test.
10:01 For more details, please write to contact @spoken-tutorial.org
10:10 Spoken Tutorial Project is a part of the Talk to a Teacher project.
10:14 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
10:20 More information on this Mission is available at the link shown below.
10:25 This is Ashwini Patil from IIT Bombay signing off.
10:28 Thank you for watching.

Contributors and Content Editors

Ashwini, Devraj, PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha