C-and-Cpp/C2/First-C-Program/English-USA

Time	Narration
00:01	Welcome to the spoken tutorial on First C program.
00:05	In this tutorial, we will learn
00:08	How to write a simple C program
00:11	How to compile it
00:13	How to execute it
00:15	We will also explain some common errors and their solutions.
00:18	To record this tutorial, I am using
00:21	Ubuntu operating system version 11.10 and gcc Compiler version 4.6.1 on Ubuntu.
00:31	To practice this tutorial,
00:33	You should be familiar with Ubuntu Operating System and an Editor.
00:38	Some editors are vim and gedit.
00:42	I will use 'gedit' in this tutorial.
00:45	For relevant tutorials please visit our website which is as shown. http://spoken-tutorial.org
00:51	Let me tell you how to write a C program through an example.
00:55	Open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard.
01:07	Now let's open the text editor. So, at the prompt, type
01:12	“gedit” space “talk” dot “c” space “&” sign.
01:20	We use ampersand (&) to free up the prompt.
01:24	Please note that all the C files will have extension “.c”(dot C).
01:30	Now Press Enter,
01:32	the text editor has opened.
01:36	Let us start to write a program.
01:39	Type double slash “//” space
01:42	“My first C program”.
01:48	Here, double slash is used to comment the line.
01:52	Comments are used to understand the flow of program.
01:56	It is useful for documentation.
01:58	It gives us information about the program.
02:01	The double slash is called as single line comment.
02:07	Now press Enter.
02:09	Type (hash) “#include” space opening bracket , closing bracket.
02:17	It is always a good practice to complete the brackets first, and then start writing inside it.
02:24	Now Inside the bracket, type“stdio” “(dot).” “h” .
02:30	stdio.h is a header file.
02:33	A program must contain this header file when it uses standard input/output functions.
02:41	Now press Enter.
02:43	type “int” space “main” opening bracket, closing bracket.
02:50	main is a special function.
02:52	It denotes that the execution of the program begins from this line.
02:58	The opening bracket and closing bracket is called as parenthesis.
03:04	Parenthesis followed by main is to tell the user that main is a function.
03:11	Here the int main function takes no arguments.
03:15	It returns a value of type integer.
03:18	We will learn about data types in another tutorial.
03:23	Now Let us switch to the slides to know more about main function. Let us go to the next slide.
03:29	Every program should have one main() function.
03:33	There should NOT be more than one main function.
03:36	Otherwise the compiler cannot locate the beginning of the program.
03:41	The empty pair of parentheses indicates that main has no arguments.
03:46	The concept of arguments will be discussed in detail in the upcoming tutorials.
03:52	Now let us come back to our program.
03:55	Press Enter.
03:58	Type opening curly bracket “{”.
04:00	The opening curly bracket marks the beginning of the function main.
04:04	Then Type closing curly bracket “}”.
04:08	The closing curly bracket indicates the end of the function main.
04:13	Now Inside the bracket press Enter twice,
04:16	move the cursor one line up.
04:20	Indentation makes the code easier to read.
04:23	It also helps to locate errors faster.
04:25	So let us give three space here
04:29	And Type “printf” opening bracket closing bracket “()” .
04:34	printf is a standard C function to print the output on the terminal.
04:39	Here, inside the brackets, within the double quotes.
04:43	Anything within the double quotes, in the printf statement, will be printed on the terminal.
04:50	Type“Talk To a Teacher backslash n”.
04:59	Backslash n “\n” signifies newline.
05:03	As a result, after execution of the printf function, the cursor moves to the new line.
05:10	Every C statement must end with a semicolon “;”.
05:15	Hence, type it at the end of this line.
05:19	Semicolon acts as a statement terminator.
05:24	Now press Enter give three space here.
05:27	And type “return” space “0” and a semicolon.
05:34	This statement returns the integer zero.
05:38	An integer has to be returned for this function because the function type is int.
05:45	The return statement marks the end of executable statements.
05:51	We will learn more about the returned values in another tutorial.
05:55	Now click on"Save" button to save the file.
06:00	It is a good habit to save files frequently.
06:03	This will protect you from sudden power failures.
06:05	It will also be useful in case the applications were to crash.
06:10	Let us now compile the program, come back to a terminal.
06:15	Type “gcc” space “talk.c” space hyphen “-o” space “myoutput”,
06:24	gcc is the compiler,
06:27	talk.c is our filename .
06:30	-o myoutput says that the executable should go to the file myoutput.
06:37	Now Press Enter.
06:39	We see that the program is compiled.
06:42	By typing ls space (hypen) -lrt, we can see that myoutput is the last file to be created.
06:54	To execute the program, type (dot slash)“./myoutput” , press Enter.
07:01	Here the output is displayed as “Talk To a Teacher”.
07:06	As I said before, return is the last statement to be executed.
07:10	Thus, after the return statement nothing will be executed. Let us try it out.
07:15	come back to our program.
07:17	After the return statement, let us include one more printf statement,
07:22	give space here, type printf opening bracket, closing bracket.
07:27	Inside the bracket within the double quotes type Welcome backslash n , at the end type a semicolon.
07:35	Now click on save.
07:37	Let us compile and execute come back to our terminal.
07:41	you can recall the previously entered commands by using up arrowkey.
07:46	That is what I did now.
07:51	We see that the second statement welcome is not executed.
07:58	Now come back to our program.
08:00	Let us write the 'Welcome' statement above the return statement.
08:06	Click on Save.
08:09	Let us compile and execute.
08:15	We see that the second printf statement welcome has also been executed.
08:23	Now let us see the common errors which we can come across. Come back to our program.
08:29	Suppose here I will miss the dot in “stdio.h”, click on Save.
08:36	Let us compile and execute .
08:41	We see that
08:43	there is a fatal error at line no.2 in our talk.c file.
08:48	The compiler cannot find a header file with the name “stdioh”. Hence it is giving an error "no such file or directory".
08:59	And the compilation is terminated.
09:03	Let us now fix the error come back to a program. Reinsert the dot “.”, click on Save.
09:11	Let us compile and execute. Yes, it is working.
09:19	I will show you another common error.
09:22	Let us switch back to the program.
09:25	Now, suppose here I will miss the semicolon at the end of the line.
09:31	Click on Save. Let us compile and execute.
09:41	We see that there is an error at line no.6 in our talk.c file. that "expected ';' (semicolon) before 'printf'".
09:51	Come back to our program.
09:54	As I said before, semicolon acts as a statement terminator.
09:58	So it will search for it at the end of the line.5 and at the beginning of the line.6.
10:06	This is line 6.
10:09	This is the last place where you can put the semicolon.
10:12	Recall that the compiler also gives the error message on line 6.
10:18	Let us try what happens if we put the semicolon here.
10:23	Click on Save .
10:26	Let us Compile and execute.
10:30	Yes, it is working.
10:32	Now come back to our program. Let us type the semicolon here at the end of this line
10:40	as it is a conventional practice to type the semicolon at the end of the line.
10:46	Now click on Save.
10:49	Let us Compile and execute. Yes it is working.
10:54	Now let us go back to our slides.
10:57	As an Assignment
10:59	Write a program to print "Welcome to the World of C"
11:02	See what happens if “\n” is not included in the printf statement.
11:08	This brings us to the end of this tutorial.
11:12	Watch the video available at the link shown below,
11:15	It summarises the Spoken Tutorial project.
11:18	If you do not have good bandwidth, you can download and watch it.
11:22	The Spoken Tutorial Project Team
11:24	Conducts workshops using spoken tutorials.
11:28	Gives certificates to those who pass an online test.
11:31	For more details, please write to contact [at] spoken hyphen tutorial dot org
11:38	Spoken Tutorial Project is a part of the Talk to a Teacher project.
11:42	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
11:47	More information on this Mission is available at the link shown below:
11:51	This is Jean Bonnet from IIT Bombay signing off. Thank you for watching.

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