Getting Started With C Langage

8/7/2019 Getting Started With C Langage

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L a n gC


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Machine language

The programs or instructions written in this language are in the form of binary

strings of (1) and (0) and these are called the binary code. It is the fundamental

language. The programs written in this language are executed directly by the

computer. The executing speed is very fast in machine language. There exists a

one to one correspondence.

Assembly language

Assembly language is similar to machine language in the sense that in most of

cases between the machine language instruction and the assembly language

instruction. However, instead of binary codes one may use symbolic codes in the

assembly language and obviously this is an advantage. For example, one might

use the symbolic code ADD instead of a binary code say 00011, to may also use

symbolic name instead of actual addresses. However, like the machine language,

the assembly language is very much dependent on the system and differs from

machine to machine.

It is called the mother language of computer. It was used for application and

system software developing.

2. High Level Languages

The programming languages which are close to human language are known as

high level languages. High level languages are programmer friendly but difficult

for hardware. The programs written in these languages are close to English

language. Other high level languages have their own rules (syntax) and character.

These languages are used in developing application software system software.

There are two further types of High Level Languages:

Procedural Language

OOP ( Object Oriented Languages)Basic , Cobol, Pascal, Fortran and C language are the examples of Procedural

Languages whereas Visual Basic, Java, C ++ , etc are the examples of OOP

languages.

Q. What are Language processors or Language

Translators ?

Ans:

Language Processor Translators

When we write any program in high-level language, it does not run directly on

the computer. Therefore, the program has to be converted into machine language.


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The program which converts source program into an object program is called

language processor has two types.

Interpreter

Compiler

Interpreters

The language processors which execute a source program by translation andexecute one instruction at a time is called interpreter. If there is any error in the

instruction it indicates the error and program executing stops. The interpreter

translates the program instruction one by one and executes them immediately. It

does not create an object program. Thus the interpreter translates the source

program each time and the program is executed. In this method of translation and

execution, the processing speed is slow and times wasting. A basic language

processor is an example of interpreter.

Compiler

The language processor that translates program written in a high levellanguage into the machine language as a whole is called the compiler. If there is

any error in the source program, the compiler specifier the error at the time of

compilation. All errors must be removed before the compilation which leads to

successful compilation of the source program. The compiler generates an

intermediate kind of file called an object file. The computer directly executes the

object file.

Source program/code

The program which we write in High level language is called source

code/source program. The source program cannot be run directly on the computer.It is translated into (binary code) or machine language for execution by the

computer.

Object Code

After compiling, the source code/source program, converts into machine

language and it is called object code/object program. The object program directly

executes on the computer.

Q. Write the Characteristics Of High Level Language?

Ans: The main characteristics of high-level language are.

1. These languages do not depend on machine but can be run on any

computer system.


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2. The program which writes in high-level language is called source

code. The source program after compiling and execution, can be run an

any computer system.

3. An American National Standards Institute (ANSI) published the

standard for computer programming languages which has a standard

syntax

4. These high level languages are very close to human languages. The

high level languages are very easy to learn and can be understood byanother programmer.

Q. Write history of C Language.

Ans : Brief History C Language

C is a general purpose programming language C was created by Dennis

Ritchie at AT&T Bell Laboratories in 1972. C language is very popular language.

C language is a mid level language. It was written as a part of the unix operating

system. The unix system and its tools written is C. C language was used and

develop system software.

ANSI.C Standard

In 1989 a new version of the language was given by the ANSI (American

National Standards Institute) standard C. This version consists of many features.

Inter nationaly, the international standards organization ISO is responsible for

standardizing C language currently the ISO C standards in thus the final authority

that constitutes the C language programming language.

Q. Write advantages of C languages?

Ans: Advantage of Language

The C language programming has its superiority. It has many advantages

these are

1. C language is unique among programming languages in the same that

it provides the convenience of a high level language such as Pascal or

Basic

2. It also allows much close control of a computers hardware.3. The better C compilers can now generate amazingly fast code. This

code is so efficient that is often difficult to produce significant speed

increases by rewriting it in assembly language.

4. C is also a well-structured language: Its syntax makes it easy to write

programs are modular and therefore easy to understand and maintain.


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5. The C language includes many features that are specifically designed

to help create large or complex programs.

6. C is portable It is easier to convert a C program to run on a different

machine that it is to convert programs written in most other language.

Q. Write the Features of C Language?

Ans: Features of C Language

Some features of C Language are given below:

Function Oriented Language

C language is based on function and we use function for programming.

Precise Compact Code

C-Language is very precise.

Vast Language

C is vast language. Each statement has multiple usage. e.g In other languages

for loop is used as counter loop but in c, for loop is used as counter and

condition.

Versatile Language

In C any problem can be solved by a variety of different tools.

Q. Write a note on Structure of C Program?

Ans: Structure of C Program

The format on the basic of which a program is written is called the structure of

the program. The structure of C program is based on the following five parts.

Preprocessor directives

The main( ) function

Begin brace

C statements or Start C programming

End braceThe first statement of C program is preprocessor directive. With the helpof this we includes the header file.

For Example

# include


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The second function of C program is main( ) and next step begins with brace

which indicates to start programming, After begining braces C programming

starts or writes C statements and ending brace shows C program closing.

# include

void main(void)

{

printf(Welcome C language)}

Preprocessor Directives

The directives can be placed anywhere in a program, but are most often used

at the beginning of a file, before main( );

The first line of the structure.

# include

might look like a program statements, but it is not . It is not part of a function

body and does not end with a semicolon, as program statements must. Instead, it

starts with a number sign (#). It is called a preprocessor directive. Recall that

program statements or instructions to the computer. A preprocessor directive, on

the other hand is an instruction to the compiler itself. A part of the compiler called

the preprocessor deals with these directives before it begins the real compilation

process.

Header Files

The use of header files is common in C. Whenever you use a library function

predefined, you will need to use a header files that contains appropriate

declarations. Header files also contain prototypes for the library functions.

Prototypes provide a way to avoid program errors. Each header file has a (.h) fileextension.

The #include Directive

The preprocessor directive # include tells the compiler to insert another file

into your source file. We should mention that you can use #include in two ways.

The angle brackets < and > surrounding the filenames.

# include

Example indicates that the compiler should begin searching for these files in

the standard INCLUDE directory. This directory holds the header files supplied

by Boarland for the system. Instead of angle brackets around the filename, you

can also use quotation marks, as in

# include my header is


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Quotation marks instruct the compiler to begin its search for the header file in

the current directory; this is usually the directory that contains the source file. You

normally use quotation marks for header files you write yourself. Quotation marks

or angle brackets work in case, but making the appropriate choice speed up the

compilation process slightly by giving the compiler a hint about where to find the

file.

The main( ) FunctionAll C programs are divide into units called Function. The main( ) is used in

the beginning of every program. It also controls the functions ofC. That main( )

is a function. Every C program consists of one or more functions this program

has only one. No matter how many function there are in a C program, main( ) is

the one to which control is passed from the operating system when the program is

run; it is the first function executed.

The word void preceding main specifies that the function main( ) will not

return a value. The second void in parentheses, specifies that the function takes

no arguments.

Curly Braces ({ })

Aftermain uses this bracket. Also use this curly brace ({) before starting

the program. We use this curly brace (}) to close the program. The number of

only curly brackets used for opening the program must be equal to the no of

closing the program.

Statements Terminator or Semicolon (;)

When any line is finished, It is very necessary to put a semicolon on its end

point. This shows that this line has finished. If semicolon is not used, the program

will give errors.

Note:

Semicolon should not be used at the end of a loop and condition otherwise the

loop and condition will stop at that point immediately. Detail structure is given

below:


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F u n c t i o n n a m e

v o i d m a i n ( v oO p e n i n gb r a c e t od e l i m i t b o d yo f f u n c t i o n

{

p r i n t f ( W e l c o m e C L

o n e s t a t e ms e m it e r me a c hp r o gs t a t e

C l o s i n gb r a c e t od e l i m i t b o d yo f f u n c t i o n

T h i s e n t i r e P r o gc o n s i s t s o f a f uc a l l e d m a i n ( )

}

Q. Write a note on C Keywords or Reserved Words

ANs: Every language has its own terminology which is called keywords or

reserved words? There are 32 reserve words in C language. C language is case

sensitive. Its compiler differentiates between upper and lower case. So it is

necessary to execute program in lower case. Some Keywords or ReservedWords

printf float const

char scanf continue

int void return

for if switch

case while staic

default else struct

do auto gets

Q. Discuss IDE of C Language.

The Integrated Development Environment System (IDE)

This is the basic structure of C language but we need (IDE) of C for C

language programming. Source program is written in (IDE). The facilities of

editing, compiling, linking and program execution of C language are available in

C (IDE). Where we can make C language setting. We can even debug our

program within the (IDE). An on line help facility is available through menu

selecting.


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[IDE]

IDE screen is displayed. However the edit window will automatically opened

with NONAME00.C. The IDE screen, which initially displays only a menu bar at

the top of the screen and a status bar below, will appear. The menu bar displayed

the menu name File, Edit, Search, Run, and so forth. The status bar tells you

what various function keys will do now, with a blank edit window awaiting us,you type program.

Explain File Menu

New

After the (IDE) display appears, you must open and edit window into

which you can type your program. You can also open an edit window by

selecting New from the File menu. This Edit windows will be given the titleNONAME00.C.

Open

If you already in the (IDE) and you want to open a File that already exists,

select Open from the File menu or(F3) on the keyboard. A dialog windowwill appear. Type in the name of the file in the Name Field, or select it from

the list displayed.Note

That only source files-those with the (.C) extension are listed.

Save

After you typed in the source file for the program, you should save your

disk. To do this, select Save from the File menu or you can create same effect

simply by pressing the [F2] function key from keyboard. A dialog box will

appear. At the top of this dialog box is a field called save editor File As Delete

temporary Name and type New Name and press [Enter]. The file will be savedunder this name.

Note

File Name only minimum one (1) character and maximum eight (8) characters

and extension (.C).

Save As


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If you want to create a new copy of any file. First open file. Then select

Save As from the File menu. A dialog box will appear. At the top of this box

is a field call Save AsEditor file As. First file name delete and types new

Name and press [Enter]. The New file will be saved under this new name.

Changing Directories

You can change the current directory by selecting the Change dir..

option from the File menu. Once you have changed directories, open will list

the source files in the new directory.Printing

To send the contents of the file in the active window to the printer, select

Print from the File menu.Dos Shell

Selecting Dos Shell from the File menu. In Dos you can delete or list files,

change directories, and perform any other Dos command. To return to the

IDE, enter the word Exit at the Dos prompt and press enter.

Quit

To exit from the [IDE], select Quit from File menu or Type [Alt + X] and

return dos prompt.Editing

The program writing and conversion in (IDE) is called editing. Always use

C functions whenever a program is written an C language. Its correct

syntax in not used, program will give errors. This program is called source

code.

Basic Editor Commands

The most important commands in any editor are those that move the cursor on

the screen and insert and delete text. Here is a list of some of the more importantcursor commands

Keyboard Key Action

Cursor up on one line


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Cursor down one line

Cursor left one character

Cursor right one character

CTRL Cursor left one word

CTRL Cursor right one word

HOME Cursor to start of line

END Cursor to end of line

PGUP Scroll one screen up

PGDN Scroll one screen down

Enter Insert line, go to next line

Backspace Delete character to left of cursor

DEL Delete character under cursor

INS Toggle insert/write over

Cut, Copy, Paste, and Clear

Once a block is marked, you can perform various operations on it. These

operations can be invoked from the Edit menu, or by typing key combination.

They make use of an internal text buffer called the clipboard. The following table

summarizes the possibilities.

Selection

from

Edit menu

Shortcut Keys Action

Cut [Shirft] [Del] Delete block and write it to

clipboard

Copy [Ctrl] [Ins] Copy block to clipboard

Paste [Shirft] [Ins] Insert block from clipboard

at cursor

Clear [Ctrl] [Del] Delete block, do not writeto clipboard


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To move a block of text, mark it, and then select Cut. The text will write to the

clipboard, replacing whatever was there before. Then position the cursor where

you want the block to go, and select Paste. The block will write at that location.

Compiling

The compiler converts the source file into object file. The object file, which has

an (OBJ) extension, contains machine-language instructions. That can beexecuted by the computer.

(Press Key F9)

A Successful Compiling

Linking

In linking function make links with their own library file. This is called linking.

When we make a program, the functions of C language used in this program havelibrary file. It extension in (.LIB). After compiling there function make link with

their own library file and in this way, an executed file is (.exe) create.

(Press Key F9)


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A successful linking

Executing a Program

If there were no errors in the compiling or linking process, your are now ready torun the program. You can do this from the (IDE) by selecting Run from the Run

menu, or by pressing the [Ctrl + F9] key combination.

The program has written a message to output screen, but not to the [IDE] screen.

To see the programs output, select user screen from the window menu, or press

[Alt+F5]

output

Welcome C Language

Pressing any key take you back to the (IDE) screen.

Notes

Compiling and linking F9

Program Execution or Run program Ctrl + F9

To see output screen Alt + F5

Q. Write a note on errors and its types.

Ans:

ERRORSNo one writes error free computer programs every time. It may be that you

were unclear on the syntax of particular statement, or that you made a typing

error. Such errors can be discovered by the compiler or by the linker, or by

various run time routines that the compiler builds into your program

automatically.


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Compiler ErrorsSuppose you have forgotten to type semicolon at the end of the statement in

FIRST.C. The result will be that, when you compile window in C. Instead ofdisplaying the success message, will show a positive number in this case, 2 in theerrors field. Click ok in the edit status window, a message window will appear atthe bottom of the screen. It will contain the following figer.

M E S S A G E

C o m p i l i n g F I R S T . C :E r r o r F I R S T . C 6 : S t a t e m e n t m i s sE r r o r F I R S T . C 6 : c o m p u n d s t a t e

6 : 4 M o d i f i e dI n s e r

Often one typing mistake will lead the compiler to issue several error

messages as happens here. It sees that the semicolon is missing. In the edit

window, the program line with the closing brace is highlighted, and the brace

itself is highlighted in a different color. This indicates the place where the

compiler found error. When it go to the brace, it realized that there should havebeen a semicolon earlier, so it signaled the errors at that point.

Linker ErrorsErrors can also appear during the linking process. For instance, suppose you

spell the word main as MAIN. (Remember that C is case sensitive language). The

program will compile correctly, but when you build or link it, the compile status

(or linker) window will show a link error. Now the message window will display

a line something like.


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M E S S A G E

C o m p i l i n g F I R S T . C :L i n k i n g F I R S T . E X EL i n k e r E r r o r : u n d e f i n e d s y m b o l _ m

6 : 4 M o d i f i e dI n s e r

The linker must find a function called main; without this, it cannot create anexecutable file. The linker does not highlight the offending line in the source file,so you may sometimes have difficulty in tracking down such errors. However, inthis case the problem should be obvious.

Logical ErrorsWhen you start writing more complex programs, you will often find that a

program compiles and links without errors, but nevertheless fails to operate asintended. In such situations you will probably want to use Cs debugger featuresto analyze whats going on. You can single step through a program, watchvariables change as each.

Statement is executed, and performs other activities to help you analyze your

programs aberrant behavior.Note: When all the errors are corrected, press [F2] to save the source file, and

then [F9] to compile and link again.


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EXERCISES

Q1. Fill in the blanks.

1. The physical devices that constitute a computer are collectively called the

_________.

2. The instruction given to the computer to program a task is called computer

_________.

3. ROM stands for___________ .

4. The CPU is the most complex___________ of the computer.

5. Thus a 300 MHz Pentium is much___________ faster than say a 100 MHz

Pentium CPU.6. It is the CPU that performs all the___________ within the computer.

7. The___________ controls the execution of instructions given to the

computer system.

8. The ___________ is used to transfer data from one device to another.

9. ALU stands for___________ .

10. The devices provide a means of feeding instruction and data into the

computer.

11. The main memory is a___________ storage memory.

12. RAM is, therefore, also known as___________ memory.

13. RAM stands for___________ .

14. The memory is one of the most important characteristics of todays PCs.

15. Main memory consists of several memory cells with___________ address.

16. The_________ language is called the mother language of computer.

17. To move a block of text, mark it, and then select _________ command.

18. A programming language is a source of _________ between the user and

the computer.

19. Every language has its own _________ for writing a computer program.

20. The Rules are called the __________ of the language.

21. Some programming languages are close to __________ languages are

called high level languages.

22. Some programming languages are close to __________ languages arecalled low level languages.

23. Three categories of computer programming languages are __________,

__________ and __________.

24. The executing speed is very fast in __________ language.


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25. The two types of low-level languages are __________ language and

__________ language.

26. The language which contains both the high level and low level language is

called __________ level language.

27. The High level language are programmer friendly but difficult for

__________.

28. There high level languages are used in developing __________ and

__________ software.

29. Basic stands for __________.

30. Cobol stands for __________.

31. Fortran stands for __________.

32. The processor has two types __________ and __________.

33. The language processors which executes a source program by translating

and execute one instruction at a time is called __________.

34. The program which we write in high level language is called __________

or __________.

35. After compiling, the source code converts into machine language, it is

called __________ code36. The source program after compiling and execution, can be run an any

__________ system.

37. C is also a __________ language.

38. C Language is based on __________.

39. C language is very __________.

40. In C language any problem can be solved by a __________ of different

tools.

41. Header files also contain prototypes for the __________ functions.

42. All C programs are divided into units called __________.

43. The __________ is used in the beginning of every program.44. C language is __________.

45. IDE stands for __________.

46. The key (F2) is used to __________ file.

47. ANSI stands for __________.

48. To compile a program __________key is used.

49. To execute a program __________ key is used.

50. __________ key is used to open a file.

51. __________ key is used to save a file.

Q3. Select the most suitable choice.

1. __________ language is used for business work.

a. Cobol b. Basic

c. Assembly d. C

2. C language is also called __________ language.

a. High level b. Mid level


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c. Low level d. Machine

3. Mistakes in a computer program are also called __________.

a. Errors b. Syntax

c. Bugs d. Non of the above

4. The C statements are normally written in __________ letters

a. Upper-case b. Reserved word

c. Lower case d. Non of the above

5. C language is a __________ language.a. Procedure oriented b. Function oriented

c. Object oriented d. Non of the above

6. __________ is an extension of header file.

a. (.h) b. (.obj)

c. (.c) d. (.cpp)

7. __________ is an extension of library file.

a. (.h) b. (.lib)

c. (.c) d. Non of the above

8. To compile a program __________ key is used.

a. F9 b. F7c. F8 d. None of the above

9. __________ key is used and save a file.

a. F5 b. F3

c. F9 d. F2


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ANSWER EXERCISE.

Q1. Fill in the blanks

1. Hardware 2. Compute software 3. Read only memory 4. Part 5 faster 6.

Calculations 7. Control Unit 8. Data bus. 9. Arithmetic logical unit 10. Input 11.

Temporary 12. Volatile 13. Random Access Memory 14. Secondary 15. Particular

16. Assembly 17. Cut 18. Commination 19. Rules 20. Syntax 21. Human 22.

Machine 23. Low level, mid level and high level 24. Machine 25. Machine,

Assembly 26. Mid 27. Hardware 28. Application, System 29. Beginners all

purposes symbolic instruction cod 30. Common business oriented language 31.

Formula Translation 32. Interprets compiler 33. Interpreter 34. Source code,

source program 35. Object 36. Computer 37. Well structured 38. Functions 39.

Precise. 40. Variety 41. Library 42. Functions 43. main( ) 44. Case sensitive 45.

Integrated Development system 46. Save 47. American National standards

institute 48. F9 49. Ctrl + F9 50. F3 51. F2.

Q3. Answers

1. a 2. b 3. a 4. c 5. b. 6. a 7. d 8. a 9 d.

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Getting Started With C Langage