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

|  Welcome to the spoken tutorial on First C program.

| How to execute it

 

|We will also explain some common errors and their solutions.  

|Ubuntu operating system version 11.10 and gcc Compiler version 4.6.1 on Ubuntu

|You should be familiar with Ubuntu Operating System and an Editor

|Some editors are '''vim''' and '''gedit'''

|I will use gedit in this tutorial

|For relevant tutorials please visit our website which is as shown

| Let me tell you how to write a C program through an example  

|'''We use ampersand (&) to free up the prompt '''

| Please note that all the '''C''' files will  have  extension dot '''“c”'''

|  Now Press '''Enter'''

|  the text editor has opened

|  Let us start to write a program  

| 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

| Now press '''Enter'''

|Type hash '''“#include”''' space opening bracket , closing bracket'''

| It is always a good practice to complete the brackets first, and then start writing inside it

| Now  Inside the bracket, type'''“stdio”''' “(dot).” “'''h” '''

|  '''stdio.h''' is a '''header file'''

|A '''program''' must contain this header file when it uses standard '''input/output functions'''

|  type '''“int” '''space''' “main” '''opening bracket,

closing bracket .

 

| | ' '''main''' is a special '''function'''  

|It denotes that the execution of the program begins from this line

|The opening bracket and closing bracket is called as parenthesis.

|  Parenthesis followed by '''main''' is to tell the user that '''main''' is a '''function'''

| Here the '''int''' '''main function''' takes no '''arguments'''  

| Now  Let us switch to the slides to know more about  '''main function'''. Let us go to the next slide.

|  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'''

| Type opening curly bracket '''“{”'''

|Then  Type  closing curly  bracket '''“}”'''

|move the cursor one line up

| Indentation makes the code easier to read

|It also helps to locate errors faster

| And  Type''' “printf” ''' opening bracket closing bracket '''“()” '''

|'''printf '''is a standard C function to print the output on the terminal  

|  Here inside the brackets, within the double quotes,

|Anything within the double quotes in the printf statement will be printed on the terminal.

|Type'''“Talk To a Teacher '''backslash '''n”'''

|Backslash n '''“\n” '''signifies newline

|As a result, after execution of the '''printf '''function, the cursor moves to the new line

| Every '''C''' statement must end with a '''semicolon “;”'''

|Now press '''Enter''' give three space here

| And type '''“return”''' space''' “0”''' and a '''semicolon'''  

| 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

| Now click on"'''Save'''" button to save the file  

|It is a good habit to save files frequently

|This will protect you from sudden power failures

|Type '''“gcc”''' space '''“talk.c”''' space hyphen “-'''o”''' space '''“myoutput”'''

| '''gcc''' is the compiler

|'''-o''' '''myoutput''' says that the executable should go to the file '''myoutput'''

|  Now Press''' Enter. '''

|We see that the program is compiled

|By typing '''ls space (hypen) -lrt''', we can see that '''myoutput''' is the last file to be created

|To execute the program, type (dot slash)'''“./myoutput” ''' press '''Enter.'''

|  As I said before, return is the last statement to be executed

|Thus after the return statement nothing will be executed. Let us try it out.

| After the '''return''' statement, let us include one more '''printf''' statement  

| give space here type printf opening bracket, closing bracket.  

|That is what I did now

|We see that the second  statements '''welcome''' is  not executed

| Now come back to our program

|Let us write the 'Welcome' statement above the return statement

|Let us compile and execute

|We see that the second '''printf''' statement ''welcome'' has also has been executed

| Suppose here I  will the miss the dot in '''“stdio.h”''' Click on '''Save.'''

 

|We see that

 

|There is a fatal error  at line no.2 in our '''talk.c''' file.

|The compiler cannot find a '''header file''' with the name '''“stdioh”'''hence it is giving an error no such file or directory.

|Let us  now fix the error come back to a   program.Reinsert the dot '''“.”'''click on save

 

| Let us compile and  execute. Yes It is working.

| I will show you another common error

| Now, suppose here i will miss the '''semicolon'''  at the end of the line  

| Click on  '''Save'''.Let us compile and execute

| We see that there is  an error at line no.6 in our talk.c file. That expected ''semicolon'' before printf.

|As   i said before semicolon acts as a statement terminator

|  This is line 6

|  This is the last place where you can put the '''semicolon'''

|Recall that the compiler also give the error message on line 6.

|Let us   Compile and execute.

|Yes it is working  

|Now come back to our program. Let us type the ''semicolon'' here at the end of this line.

 

| As it is a conventional practice to type  the ''semicolon'' at the end of the line.

| Now click on '''Save.'''

 

|   Let us   Compile and execute. .Yes it is working.

 

| This brings us to the end of this tutorial  

|It summarises the Spoken Tutorial project  

|Conducts workshops using spoken tutorials  

|Gives certificates to those who pass an online test  

| 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