C-and-C++/C2/First-C++-Program/English

Title of script: First C++ program

Author: Ashwini

Keywords: C++ Program, cout<<, cin>>, int main(), Video Tutorial

Visual Cue	Narration
Slide 1	Welcome to the spoken tutorial on First C++ program.
Slide 2 Learning Objectives	In this tutorial I am going to explain, How to write a C++ program. How to compile it. How to execute it. We will also explain some common errors and their solutions.
Slide 3 System Requirements	To record this tutorial, I am using Ubuntu operating system version 11.10 and G++ Compiler version 4.5.2 on Ubuntu.
Slide 4 Prerequisites	To practice this tutorial, You should be familiar with Ubuntu Operating System and an Editor Some editors are vim and gedit. I am using gedit in this tutorial. For relevant tutorial Please visit our website which is as shown: http://spoken-tutorial.org
Open the Terminal Open the terminal using Ctrl + Alt + T	Let me tell you how to write a C++ program through an example Open terminal Window using Ctrl, Alt and T keys simultaneously on your keyboard.
gedit talk.cpp &	To open the text editor, type on the terminal “gedit” space “talk” dot “.cpp” space ampersand “&” sign
Highlight &	We use the “&” to free up the prompt.
Highlight .cpp	Please note that all the C++ files will have the extension “.cpp”
	Now Press Enter The text editor has opened.
	Let us start to write a program.
//My first C++ program	Type double slash “//” space “My first C++ program”.
Highlight //	Here, double slash is used to comment the line Comments are used to understand the flow of program It is useful for documentation It gives us information about the program The double slash is called as single line comment.
Type #include <>	Now press Enter Type hash “#include” space opening angle bracket “<” closing angle bracket “>”. It is a good practice to complete the brackets first, and then start writing inside it
Type #include <iostream>	Now, inside the bracket, type “iostream”.
	Here iostream is a header file This file includes the declaration of basic standard input output functions in C++.
Type using namespace std;	Now press Enter Type “using” space “namespace” space “std” and a semicolon “;”
Highlight using Highlight namespace Highlight std	The using statement informs the compiler that you want to use the std namespace The purpose of namespace is to avoid name collisionsis It is done by localizing the names of identifiers It creates a declarative region and defines a scope Anything defined within a namespace is in the SCOPE of that namespace Here, std is the namespace in which entire standard C++ library is declared.
Type int main()	Now Press Enter. Type “int” space “main” opening bracket “(” closing bracket “)” .
Highlight main()	Main is a special function It denotes that the execution of the program begins from this line. The opening and the closing bracket is called as parenthesis.
Highlight ()	Parenthesis followed by main tells the user that main is a function.
Highlight int main()	Here the int main function takes no arguments and returns a value of type integer.
	We will learn about data types in another tutorial.
	Now let us switch to the slides to know more about the main function.
	Every program should have one main function There should NOT be more than one “main” function Otherwise the compiler cannot locate the beginning of the program The empty pair of parentheses indicates that main has no arguments The concept of arguments will be discussed in the upcoming tutorials. Now come back to our program.
Type {	press Enter. Type opening curly bracket “{” The opening curly bracket marks the beginning of the function main.
Type }	Then type closing curly bracket “}” The closing curly bracket indicates the end of the function main. Now inside the bracket press enter twice Move the cursor one line up.
	Indentation makes the code easier to read It also helps to locate errors faster. So let us give a space here.
Type cout <<	And type “cout” space two opening angle bracket “<<”
Highlight cout<<	Here cout is a standard C++ function to print the output on the terminal
Type cout << “Talk to a teacher\n”	Now after the brackets, type within the double quotes
Highlight “”	Anything within the double quotes in the cout << function will be printed. Now inside the quotes type “Talk to a teacher backslash \n”.
Highlight \n	Here \n signifies newline As a result, after execution of the cout function, the cursor moves to the new line.
Type “;”	Every C++ statement must end with a semicolon Hence type it at the end of this line.
Highlight ;	Semicolon acts as a statement terminator.
Type return 0;	Now press Enter. Give a space here And Type “return” space “0” and a semicolon “;”.
Highlight return 0; Highlight int	This statement returns the integer zero. An integer has to be returned for this function. Because the function type is int. The return statement marks the end of executable statements. We will learn more about the returned values in another tutorial.
Save	Now click on the “Save” button to save the file. It is a good habit to save files frequently. This will protect you from sudden power failures. It will also be useful in case the applications were to crash.
Compile	Let us now compile the program.
Type g++ talk.cpp -o output	Come back to our terminal Type “g++” space “talk.cpp” space hyphen “-o” space “output”.
Highlight g++ Highlight talk.cpp Highlight -o output	Here g++ is the compiler used to compile C++ programs talk.cpp is our filename -o output says that the executable should go to the file output. Now press Enter.
	We see that the program is compiled.
Type ls -lrt	By typing ls space -lrt, we can see that output is the last file to be created.
Type ./output	Let us execute the program, type dot slash “./output” And Press Enter.
Highlight Talk to a teacher	Here the output is displayed as “Talk to a teacher”.
Errors	Now let us see the common errors which we can come across Switch back to our text editor.
{	Suppose here we miss the closing curly bracket}
	Now save the file.
	Let us execute Come back to our terminal
	Now compile and run the program using the commands we used before.
Highlight error Highlight Line no.7 Highlight talk.cpp Highlight {	We see an error. 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.
	Now Come back to our text editor.
	As I said before the closing curly bracket marks the end of the function main Hence reinsert the bracket here.
	Now Save the file.
	Let us execute it again. You can recall the previously entered commands by using up arrow key That is what I did now Yes it is working.
Error 2	I will show you another common error Let us switch back to our text editor.
	Now, suppose here we missed std.
	let us Save the file.
Highlight error Highlight Line no.3 and 6 Highlight talk.cpp Highlight ; Highlight cout	Come back to our terminal.Let us Compile. We see that there is an error at line no 3 and 6 in our talk.cpp file that expected identifier before semicolon and cout was not declared in this scope.
	As cout is the standard C++ library function and the entire C++ library function is defined under std namespace Hence it is giving an error.
	Let us now fix the error Come back to our text editor. type std. here
	Let us Save it.
	Let us compile it again Yes it is working.
	As an assignment, Write a program to print your name and city We used single line comment in this tutorial Now just try to give multiline comment Hint: /*.................. .....................*/
Slide 8 About the Spoken Tutorial Project	Watch the video available at the link shown below http://spoken-tutorial.org /What\_is\_a\_Spoken\_Tutorial It summarises the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it.
Slide Number 9 Spoken Tutorial Workshops	The Spoken Tutorial Project Team Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, please write to contact@spoken-tutorial.org
Slide Number 10 Acknowledgement	Spoken Tutorial Project is a part of the Talk to a Teacher project It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at the link shown below : http://spoken-tutorial.org\NMEICT-Intro
	This is Ashwini Patil from IIT Bombay signing off Thank you for joining

Contributors and Content Editors

Ashwini, PoojaMoolya