Difference between revisions of "C-and-C++/C2/First-C-Program/English-timed"

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Revision as of 17:41, 9 July 2014

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
00:14 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
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 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 programshould 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 statements 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 has 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 the miss the dot in “stdio.h” Click on save.


08:36 Let us compile and execute .
08:41 We see that
08:42 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 give 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 Ashwini Patil from IIT Bombay signing off. Thank you for watching.
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